Here’s a concise overview of the Offline Update feature in ESET products (e.g., ESET NOD32 Antivirus, ESET Internet Security, ESET Endpoint Antivirus):
If you rely on the ESET offline update method regularly (e.g., for a factory floor with no internet), follow these pro-tips.
Overall Rating: ⭐⭐⭐⭐ (4/5)
Best for: Air-gapped PCs, limited-bandwidth environments, or systems with unstable internet.
For IT pros who want to automate the process, you can use a batch script on the target machine. This script assumes the USB drive is always inserted as E:\ when the admin is present.
# Force ESET Offline Update via Script
# Run as Administrator
It allows you to manually download the latest virus signature database on a connected computer and then transfer and apply it to an offline machine running ESET antivirus.
Limited Documentation
ESET’s help files cover the basic steps, but troubleshooting (e.g., “Module not up to date”) often requires searching forums.
The ESET offline update method is not a convenience feature; it is a lifeline for disconnected systems. By mastering the three methods—the Official Tool, Manual ZIP, or Local Mirror—you ensure that even your most remote or secure machines receive the latest threat intelligence.
Remember the golden rule of offline security: Trust nothing, verify everything. Always scan your update source before disconnecting it from the internet, and maintain a strict schedule for refreshing your offline update packs.
For the latest offline update files and tool versions, bookmark the official ESET Knowledgebase (KB) or contact your enterprise account manager. Your offline network’s safety depends entirely on the quality and currency of your update process.
Disclaimer: This article is for educational purposes. Always refer to ESET’s official documentation for version-specific paths and support.
Introduction
In today's connected world, cybersecurity is a top priority for individuals and organizations alike. ESET, a renowned cybersecurity company, offers a range of products and services to protect against various types of malware and online threats. One of the key features of ESET's products is the offline update capability, which allows users to update their ESET software even without an active internet connection. In this article, we'll explore the concept of ESET offline update, its benefits, and how to perform it.
What is ESET Offline Update?
ESET offline update is a feature that enables ESET users to update their software with the latest virus definitions and program updates without requiring an active internet connection. This feature is particularly useful for users who have limited or no internet access, or those who want to ensure their ESET software is up-to-date before connecting to the internet.
Benefits of ESET Offline Update
The ESET offline update feature offers several benefits, including:
How to Perform ESET Offline Update
To perform an ESET offline update, you'll need to:
Best Practices for ESET Offline Update
To ensure a smooth and successful offline update, follow these best practices:
Conclusion
In conclusion, ESET offline update is a valuable feature that allows users to keep their ESET software up-to-date even without an active internet connection. By understanding the benefits and process of offline updates, users can ensure their devices are protected against the latest threats and malware, while also enjoying the convenience and reduced bandwidth usage that offline updates offer.
To update ESET offline, you must first create a local update mirror on a machine with internet access or use the ESET Mirror Tool. Offline updates are typically a feature of ESET Endpoint (business) products; home products generally require an active internet connection to update.
Method 1: Creating a Local Update Mirror (Business Versions)
If you have at least one computer with internet access, you can set it up to act as a server for offline machines. On the Internet-Connected Machine: Open ESET and press F5 to access Advanced Setup. Go to Update → Profiles → Update Mirror. Toggle Create update mirror to enabled.
Click Edit next to Storage folder and select a folder to save the update files.
Ensure Enable HTTP Server is toggled on to allow other machines to fetch these files. On the Offline Machine: Open ESET and press F5 for Advanced Setup. Go to Update → Profiles → Updates. Disable Choose automatically.
In the Custom server field, enter the IP address of your mirror server (e.g., http://192.168.1.10:2221). Method 2: Using the ESET Mirror Tool
For environments without any managed internet access for the security application, use the ESET Mirror Tool to download updates to a portable drive. Offline Repository—Windows | ESET PROTECT On-Prem 13.0
Title: The Last Signature
Setting: Sector 4 (The "Gray Zone"), 30 clicks from the Detroit Sprawl.
Protagonist: Kael, a data-scavenger running a legacy security rig.
The air inside the cockpit of The Dredger smelled like ozone and stale recycled coffee. Outside, the acid rain drummed a relentless rhythm against the polarized glass, blurring the neon bleed of the distant city into watercolor smears.
Kael ignored the view. His eyes were locked on the holo-screen projected from his dashboard. A single, blinking amber light.
SYSTEM STATUS: THREAT DETECTED.
ENGINE VERSION: 4.2.1 (OBSOLETE).
MODULE: ESET Cyber Security - HEURISTIC ANALYSIS: FAILED.
"C'mon, you piece of antique junk," Kael whispered, tapping the manual override. "Don't do this to me now."
He was hauling a sealed server rack he’d dug out of a sunken corporate bunker—a score big enough to buy him six months of clean water and real meat. But the rack was air-gapped, paranoid, and protected by a dormant, mutated strain of polymorphic malware. To access the data without triggering the wipe protocol, he needed to run a security scan. But his rig was too old. The definitions were months out of date.
The connection to the global grid had been spotty for weeks. The Corporations were fighting again, jamming the frequencies. Kael didn't have the bandwidth to download a 400-megabyte update package over the air.
He needed to go offline.
"Initiating ESET Offline Update protocol," Kael muttered, reaching under his seat for the heavy, ruggedized drive he kept there.
It was an archaic method, something the old-school runners called "Sneakernet." In a world of cloud-syncing neural links, carrying data physically was considered barbaric. But barbaric was reliable.
He slotted the drive. The system chirped.
SOURCE: EXTERNAL. INITIALIZING...
LOADING UPDATE FILE: NOD32_V92.0.12.SIG
The progress bar crept forward. Ten percent. Twenty.
The lights in the cockpit flickered. The server rack behind him let out a low, mechanical whine. The malware inside was sensing the intrusion. It was waking up.
"Easy, boy," Kael said, his hand hovering over the emergency eject button. If the scan failed, the malware would bridge the connection and fry his ship’s nav-system. He’d be dead in the water, waiting for the scavengers to pick his bones.
ERROR. VERIFICATION FAILED.
Kael froze. "What?"
The screen flashed red. SIGNATURE FILE CORRUPTED. INTEGRITY CHECK: FAIL.
He ripped the drive out and stared at it. The casing was cracked. Moisture from the humid air must have seeped in. He had a dead file, and a waking monster.
The server rack began to click rapidly. The cooling fans screamed. The malware was executing a counter-offensive. A warning siren blared in the cockpit.
BREACH IMMINENT. NETWORK INTRUSION DETECTED.
Kael slammed his fist against the console. He was out of time. He couldn't download the update, and his local file was trash. He was about to lose everything.
Then, he saw it. A tiny, flickering icon in the corner of his HUD. The Local Cache.
ESET’s architecture had a failsafe for just this kind of hell. Even if the primary update file was corrupted, the engine maintained a shadow copy of the last known good configuration in the system kernel, isolated from the main drive. It wasn't the newest update. It wasn't the version 92 he was trying to load. It was version 88. Ancient history.
But it was clean.
"System," Kael barked. "Rollback. Load offline repository. Version 88."
WARNING: LEGACY ENGINE MAY NOT DETECT ZERO-DAY THREATS.
"It's not a zero-day if it's a twenty-year-old bunker virus!" Kael shouted. "Execute!"
The drive whirred. The progress bar didn't creep this time; it slammed forward.
LOADING OFFLINE REPOSITORY...
APPLYING SIGNATURES...
ARCHIVE PROCESSING: 100%.
The cabin went silent. The server rack’s screaming fans died down to a low hum. The red warning lights dissolved into a soothing, reassuring blue.
THREAT NEUTRALIZED.
QUARANTINE INITIATED.
FILES SECURE.
Kael slumped back in his pilot’s chair, exhaling a breath he felt he’d been holding for an hour. He looked at the screen. The data on the server rack was decrypting. It was safe.
He patted the dashboard of the old ship. Sometimes, the cloud let you down. Sometimes the grid failed you. But a good offline update, stored deep in the local memory, was like a loaded gun in a knife fight.
"Legacy systems for the win," he smiled, engaging the thrusters to head back to the Sprawl.
UPDATE COMPLETE.
For environments where computers are not connected to the internet, ESET provides several ways to keep security modules up-to-date. This is primarily a feature for ESET Endpoint business products. 🛠️ Common Methods for Offline Updates
Mirror Tool: Use the ESET Mirror tool on a machine with internet access to download all necessary updates. These files can then be transferred via a USB drive or network share to the offline machines.
Update Mirror (Internal Server): You can configure an ESET product on a networked (but isolated) machine to act as a local update mirror. It downloads updates once and serves them to other clients on the local network via HTTP or a shared folder.
Offline Repository: For environments managed by ESET PROTECT, you can set up an offline repository address in the policy settings to direct clients to a local source for both module and product updates. 📝 Step-by-Step Configuration (Standalone Client)
To manually update a standalone machine from a local folder:
ESET offline updates allow computers in closed environments or with restricted internet access to maintain protection by downloading module and application updates from a local "mirror" rather than directly from ESET servers. This process typically involves a machine with internet access using the ESET Mirror Tool to create a repository of updates, which is then served to offline clients via an internal HTTP server or a shared network folder. Offline Update Infrastructure
For environments without internet connectivity, ESET provides several ways to distribute updates locally:
Mirror Tool: This is the primary method for creating an offline repository. It downloads all necessary update modules and metadata from ESET servers to a local directory. Update Mirror (HTTP Server) : An ESET product (like ESET Endpoint
) can be configured as a mirror to share updates with other computers in the same network.
ESET Bridge (Proxy): If at least one computer has internet access, ESET Bridge can cache update files locally, significantly reducing external traffic by downloading files once and serving them to all other clients. Configuration Steps 1. Setting up the Local Mirror On the computer that will serve as the update source: Open the ESET program and press F5 for Advanced Setup. Navigate to Update → Profiles → Update Mirror. Enable the Create update mirror toggle. Specify a Storage folder path where updates will be saved.
Enable HTTP Server and, if needed, set a username, password, or custom port. 2. Configuring Offline Clients To direct client machines to the local mirror: Open Advanced Setup (F5) on the client machine. Go to Update → Profiles → Updates. Disable Choose automatically under Module Updates.
In the Custom server field, enter the IP address of your mirror (e.g., http://10.20.30.50:2221). Key Considerations
License Files: Managing updates in a completely offline environment requires an offline license file (.lf), which can be generated through the ESET Business Account or ESET PROTECT.
Product Types: Offline updates are generally a feature of ESET business/endpoint products. Most home products, like ESET NOD32 Antivirus, do not support offline updating.
Maintenance: Regularly clear the Update Cache if you encounter errors. This is done via Advanced Setup → Update → Clear update cache. Available Tools & Documentation Mirror Tool Create offline repositories for updates ESET Mirror Tool Guide ESET PROTECT Remote management for offline policies ESET PROTECT Online Help Advanced Setup Manual configuration on single devices ESET Endpoint Security Help
If you'd like, I can help you troubleshoot a specific update error or provide a step-by-step setup for a specific ESET version.
In high-security environments, such as government agencies or air-gapped corporate networks, keeping security software current without a direct internet connection is a critical challenge. The ESET offline update process solves this by allowing machines to receive detection engine and module updates via a local mirror or removable media. Why Use ESET Offline Updates?
Air-Gapped Systems: Protects critical infrastructure that must remain disconnected from the public internet.
Bandwidth Conservation: Reduces external network traffic by downloading updates once to a central "mirror" server instead of each client downloading them individually.
Compliance: Meets strict regulatory requirements for closed-network security. Step 1: Prepare the Mirror Tool
The ESET Mirror Tool is a standalone utility that creates a local repository of update files.
Download the Tool: Obtain the MirrorTool.exe from the ESET Standalone Installers page on a machine with internet access.
Get an Offline License: Log in to ESET Business Account or ESET PROTECT Hub to generate and download an offline activation file (.lf). This is mandatory for the Mirror Tool to authorize downloads.
Run the Initial Download: Use the Command Prompt to trigger the download. A typical command looks like this: eset offline update
MirrorTool.exe --mirrorType regular --offlineLicenseFilename c:\mirror\offline.lf --outputDirectory C:\mirror\out Use code with caution.
This creates a structured update repository in your output folder. Step 2: Distribute Updates to Offline Clients
Once you have the repository, you can deliver it to offline machines using two primary methods: Method A: Removable Media (USB/CD)
For completely isolated machines, manually transfer the repository. Mirror Tool - Windows | ESET PROTECT On-Prem 12.0
Title: The Strategic Necessity and Execution of ESET Offline Updates
Introduction
In an era dominated by always-on internet connections and cloud-computing, the concept of "offline" software management often seems antiquated. However, for cybersecurity—specifically regarding antivirus solutions like those provided by ESET—offline updates remain a critical operational component. While the default mode of operation for ESET security products is to retrieve virus signature database updates directly from ESET servers via the internet, there are specific environments where this is impossible or unsafe. The process of an "ESET offline update" involves manually downloading the latest threat detection signatures and installing them on a target computer without a direct internet connection. This practice is not merely a redundancy; it is a vital security measure for air-gapped networks, secure facilities, and troubleshooting scenarios where the standard update mechanism fails.
The Rationale for Offline Updates
The primary driver for offline updates is the existence of isolated or "air-gapped" networks. Many corporate, government, and military environments operate highly sensitive systems that are deliberately disconnected from the public internet to prevent data exfiltration and remote hacking attempts. In these scenarios, the endpoint computers cannot reach ESET’s update servers. Without a mechanism to inject new threat definitions, the antivirus software would rapidly become obsolete, rendering the air-gap useless against malware introduced via removable media.
Furthermore, offline updates serve as a crucial troubleshooting tool. It is not uncommon for system updates, firewall misconfigurations, or corrupted temporary files to break an antivirus program’s ability to connect to its update servers. In such cases, an offline update acts as a manual override, forcing the software to recognize the latest signatures and often resetting the internal update logic, thereby restoring the software’s functionality.
The Mechanism: Mirror Tool and Installation
Executing an ESET offline update is a structured process that requires intermediate hardware. The standard method involves using the ESET Mirror Tool. An administrator runs this tool on a computer that does have internet access. The Mirror Tool connects to the ESET update servers and downloads the latest virus signature database and software component updates. It then packages these files into a specific folder structure, often saved to a USB drive or a network share.
Once the update files are transferred to the removable media, the physical media is moved to the isolated (target) computer. The administrator then configures the ESET endpoint on the target machine to look for updates from a "Local Directory" rather than the internet. By browsing to the folder on the USB drive where the update files are stored, the ESET software treats the USB drive as a makeshift server. It verifies the digital signatures of the files and applies the updates, bringing the virus database current. This method ensures that even without a direct pipeline to the vendor, the endpoint retains its defensive capabilities.
Challenges and Risks
While offline updates solve a connectivity problem, they introduce logistical challenges. The most significant is the "update latency." A computer connected to the internet can receive signature updates every hour; an offline computer relies on a human administrator to perform the transfer. If the administrator waits a week between offline updates, the system is vulnerable to any zero-day threats discovered during that window.
Additionally, the integrity of the transfer medium—typically a USB drive—is paramount. If the USB drive used to transport the ESET updates is infected with malware from an external network, it could bridge the air-gap and compromise the secure system. To mitigate this, secure environments often employ strict scanning protocols on the transfer device before it is plugged into the secure network, or they use write-protected hardware to prevent the drive from picking up malicious code during the transfer process.
Conclusion
The "ESET offline update" represents the intersection of rigorous security protocols and practical system administration. It acknowledges that while the internet is the standard vector for cybersecurity maintenance, it cannot be the only one. For high-security environments where connectivity is a liability rather than a utility, the ability to manually port threat definitions is the only way to maintain a functional defense posture. By understanding the mechanics of the Mirror Tool and the importance of secure transfer protocols, IT professionals can ensure that even the most isolated systems remain protected against the evolving landscape of digital threats.
Offline updates allow ESET products to stay current without an active internet connection on the target machine. This is typically achieved by downloading update files on an online computer and transferring them via removable media. 🛠️ How to Perform an ESET Offline Update
To update your ESET software manually, you need to configure the program to look for local files instead of ESET’s online servers. Step 1: Download Update Files
You must first obtain the offline update modules. These are often provided as a .zip or directory of files from the ESET Update Server or through an ESET Mirror. Step 2: Configure Advanced Setup
Open your ESET product and press F5 to enter Advanced Setup. Navigate to Update > Profiles > Updates. Locate the Update type or Update server setting.
Select Choose automatically or manually enter the path to the folder containing your offline update files (e.g., D:\ESET_Updates). Step 3: Trigger the Update Return to the main program window. Click Update in the left-hand menu.
Select Check for updates to begin the process from your local source. 💡 Key Benefits of Offline Updates
Air-Gapped Security: Keep high-security systems protected without exposing them to the internet.
Bandwidth Savings: Download updates once and distribute them to multiple machines on a local network.
Stable Environments: Use specific module versions that have been vetted for stability before deployment. ⚠️ Important Considerations
License Validity: Even for offline updates, your ESET product requires a valid license to function and process the modules.
File Freshness: Antivirus signatures become outdated quickly; ensure you download the latest offline files daily to maintain protection.
Feature Limits: Some cloud-based features, like ESET LiveGrid, may not function properly without an occasional internet handshake. Module update | ESET Server Security for Linux 11.0
ESET security products are designed to receive regular virus signature updates via the internet to protect against the latest threats. However, in high-security environments, air-gapped systems, or locations with limited connectivity, a traditional internet-based update is not possible. This is where an ESET offline update becomes essential. Understanding ESET Offline Updates
An offline update allows you to keep your ESET antivirus or endpoint security software current without a direct connection to ESET's update servers. This process involves downloading the necessary update files on a machine with internet access and then transferring them to the offline computer via a removable medium, such as a USB flash drive or an internal network share. Why Use Offline Updates?
Air-Gapped Systems: Protecting sensitive computers that are physically isolated from all networks.
Bandwidth Conservation: Updating multiple machines on a slow network by downloading the files only once.
Network Security: Minimizing the number of devices with outbound internet access.
Server Stability: Ensuring servers in restricted environments remain protected. How to Perform an ESET Offline Update
The process differs slightly depending on whether you are managing a single standalone machine or a large network via ESET PROTECT.
Method 1: Using the ESET Mirror Tool (Recommended for Businesses)
The Mirror Tool is the official utility for creating a local repository of update files.
Download the Tool: Obtain the ESET Mirror Tool from the ESET website on a computer with internet access.
Create a Folder: Create a destination folder for the update files (e.g., C:\ESET_Updates).
Run the Command: Execute the tool via Command Prompt. A typical command looks like:MirrorTool.exe --mirrorType regular --intermediateUpdateDirectory C:\temp --offlineLicenseFilename license.lf --outputDirectory C:\ESET_Updates
Transfer Files: Copy the contents of the output directory to your offline machine or a local server. Configure the Client: Open your ESET product. Press F5 for Advanced Setup. Navigate to Update > Profiles > Updates.
In the Update server field, enter the path to the folder (e.g., file:///C:/ESET_Updates). Method 2: Manual Update for Home Users Here’s a concise overview of the Offline Update
For individual users without access to the Mirror Tool, ESET provides offline update modules (legacy support varies by region and product version).
Download Update Files: Access the ESET offline update page to download the latest .zip archive of the detection engine.
Extract Files: Unzip the archive into a dedicated folder on the offline PC.
Update Path: In the ESET software settings, change the update server to point to the local folder path where you extracted the files.
Trigger Update: Click "Check for updates" in the main program window. Best Practices for Offline Maintenance
Maintaining security in an offline environment requires a disciplined routine.
Frequency: Aim to perform an offline update at least once every 24 to 48 hours to defend against zero-day threats.
License Management: Ensure you have an offline license file (.lf) exported from ESET Business Account, as the software cannot verify subscriptions online.
Automation: If the offline machine is on a private LAN, host the update files on a local HTTP server or shared drive to automate updates for multiple clients.
Validation: Always verify the "Last successful update" timestamp in the ESET GUI to ensure the local path is working correctly. Troubleshooting Common Issues
Modules Out of Date: Ensure you are downloading the full set of modules, not just the detection engine.
Invalid License: Offline updates usually require a specific offline license file to be uploaded during the Mirror Tool configuration.
Path Errors: When entering a local file path, use the format file:/// followed by the drive letter and folder.
By implementing a robust offline update strategy, you can enjoy the industry-leading protection of ESET even in the most restricted digital environments.
ESET offline update is a critical feature designed for computers or networks that do not have direct access to the internet. This "air-gapped" security method ensures that even isolated systems remain protected against the latest malware by manually transferring virus signature databases from an online machine. Why Use Offline Updates? High-Security Environments
: Ideal for government, military, or research labs where internet access is restricted to prevent data leaks. Bandwidth Conservation
: In locations with expensive or limited internet, one machine can download updates and distribute them locally. Unstable Connections
: Systems in remote areas can be updated via physical media (USB drives) when a stable web connection is unavailable. Methods for Offline Updating
Depending on your version and setup, ESET provides different tools to facilitate this: ESET Mirror Tool
: This is the official utility for creating an offline repository. It downloads detection engine updates and program modules from ESET servers and saves them to a local folder or shared network drive. Update Mirror Feature
: Some ESET Endpoint versions allow you to designate one computer as a "Mirror." This machine downloads updates and acts as a local server for other workstations in the same network. Offline License Files
: To enable these features, you typically need an offline license (.lf) file from the ESET Business Account
portal, which authorizes the software to update without contacting ESET's online activation servers. ESET Knowledgebase How to Set It Up (General Steps) Generate License : Log into your ESET account and download an offline license file Create Repository Mirror Tool
on a machine with internet access to download the update files to a USB or internal drive. Configure Client : On the offline computer, go to Advanced Setup (F5) Point to Source
: Set the "Update Server" or "Update Mirror" path to the folder where you stored the downloaded files. ESET Knowledgebase For detailed technical walkthroughs, the ESET Knowledgebase provides step-by-step guides for Endpoint versions Server products step-by-step guide
for a particular version of ESET, such as Endpoint Security or ESET PROTECT?
Maintaining cybersecurity in "closed" or air-gapped environments requires a strategic approach to software updates. For organizations using ESET, offline updates ensure that workstations without internet access remain protected against the latest threats by manually or locally synchronizing detection engine modules. The Core Strategy: The Mirror Tool
The primary method for updating ESET products offline is using the ESET Mirror Tool. This tool allows a computer with internet access to download the necessary update files and act as a "mirror" for machines that are restricted from the web.
Offline Repository: You can create a local clone of the ESET repository, which can be moved via external media (like a USB drive) to the secure, offline network.
Infrastructure Requirements: A full offline repository currently requires approximately 1.2 TB of free storage space. Implementation Process
Preparation: Download the Mirror Tool and obtain an offline license file (.lf) from the ESET Business Account or ESET PROTECT Hub.
Creation: On an internet-connected PC, run the Mirror Tool via Command Prompt to download updates to a specific output directory. Distribution:
Local Web Server: Host the downloaded files on an internal HTTP server (e.g., ESET Bridge) so clients can download them via the LAN.
Removable Media: For truly isolated machines, copy the mirror content to a removable drive and point the client's update path to that local folder.
Client Configuration: In the ESET product's Advanced Setup, navigate to the Update section. Change the update server to the URL or file path of your local mirror. Why Offline Updates Matter Offline Repository—Windows | ESET PROTECT On-Prem 13.0
To perform an ESET offline update , you typically use the Mirror Tool
to create a local update repository on a machine with internet access, which can then be transferred to an offline network via an external drive or local network share. Core Offline Update Methods Mirror Tool (Recommended for Networks):
A standalone utility that downloads ESET update modules to a local folder. You can then share this folder via an HTTP server or a network path (UNC) for other client machines to use. Offline Mirror Feature:
Certain ESET endpoint products can be configured to act as a "mirror server" themselves. You enable this in Advanced Setup (F5) > Update > Profiles > Update Mirror Manual Folder Import:
For individual legacy or standalone machines, you can copy the update files (often
files) from an updated machine's cache and point the offline machine's update path to that local folder. Step-by-Step: Setting Up an Offline Update Mirror Download the Mirror Tool : Obtain the tool from the ESET official download page Generate an Offline License : Log in to the ESET Business Account ESET PROTECT Hub and create an offline license file ). This file is required to authorize the Mirror Tool. Run the Tool : Use the command line to start the download.
MirrorTool.exe --mirrorType regular --offlineLicenseFilename c:\mirror\offline.lf --outputDirectory C:\mirror\out Configure Clients : On the offline machine, open ESET and press Advanced Setup Navigate to Update > Profiles > Updates Choose automatically and enter the local folder path or local server IP (e.g.,
Here’s a clear, instructional text for ESET Offline Update:
ESET Offline Update – Keep Your Antivirus Up to Date Without an Internet Connection Limited Documentation ESET’s help files cover the basic
If you manage computers that cannot connect to the internet, or you need to update ESET products in an isolated network, use the ESET Offline Update method.