Google Chrome update fixes this annoying Windows 10 antivirus bug

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A bug that enabled antivirus software on computers running Windows 10 to lock newly created files has been fixed in Google Chrome and other Chromium-based browsers.

Now that this bug has been patched, antivirus software running on Windows is no longer able to block new files such as bookmarks generated by the Chrome web browser.

In order to protect users' systems from malware and other viruses, many antivirus programs have the capability to temporarily lock newly created files until they have been scanned to ensure they are not malicious. This feature has led to issues on Windows 10 machines running Chrome as the browser would use ImportantFileWriter to output certain files as explained by Google engineer Bruce Dawson in a recent post on the Chromium Gerrit:

“Anti-virus programs and other scanners may briefly lock new files which can lead to frequent problems with saving bookmarks and other files that use the ImportantFileWriter.”

As a result, Windows 10 users running antivirus software on their systems would experience issues trying to save bookmarks and other files as Chrome would have difficulty creating the corresponding file.


In order to resolve this Windows 10 antivirus bug, a fix has been added to Chromium's Google Source codebase that affects all Chromium-based browsers.

The fix itself executes the command ReplaceFile multiple times in order to bypass the possible race condition in which an antivirus program takes control of and locks a file being accessed by Chrome at the same time. There is also a machine learning aspect to the fix as Chrome will teach itself to fine-tune the number of attempts needed to bypass these race conditions over time.

According to Dawson, the bug only impacts Windows systems and this is why the fix was made to ImportantFileWriter as it is specific to Microsoft's operating system.

As the fix was merged into the Chromium repository late last month, it is expected to be included in the next version of Google Chrome when it ships. This is why it is recommended that Windows 10 users running antivirus software promptly update Chrome when future updates become available.

Via BleepingComputer

Anthony Spadafora

After working with the TechRadar Pro team for the last several years, Anthony is now the security and networking editor at Tom’s Guide where he covers everything from data breaches and ransomware gangs to the best way to cover your whole home or business with Wi-Fi. When not writing, you can find him tinkering with PCs and game consoles, managing cables and upgrading his smart home.