UiPath Extension Firefox not working on Firefox Version 135.0

[Luiza_Surdu-Bob (Luiza Bob)]

Hello everyone,

The latest Firefox update to version 135.0 introduced a breaking change affecting the UiPath extension for Firefox. This causes Firefox browser automation processes to fail.

Our team is working on this issue and preparing a fix to be released this week. We will update this post as soon as we have news.

Available workaround

Until then, the immediately available workaround is to downgrade Firefox from version 135.0 to an earlier version.

You also need to change your Firefox update settings to prevent Firefox from automatically updating itself after you install an older version (see https://support.mozilla.org/en-US/kb/install-older-version-firefox?redirectslug=install-older-version-of-firefox&redirectlocale=en-US)

[jacek.jusyn]

You may also need to make the updates in update-config.json file that sits in ProgramData folder on C drive, so that your firefox does not get updated automatically after downgrade.

[dylan.kelly]

Is there any actual fix at this time?

[dylan.kelly]

Is there any form of official fix? Downgrading to a prior version seems like such a tedious fix for everyone.

Why would we prevent auto updates? That usually entails key security features and protocols. How can UI path just not keep up with extension support?

[Luiza_Surdu-Bob (Luiza Bob)]

Hello @dylan.kelly,

Preventing auto updates was only suggested as part of the workaround.

Disabling automatic updates would only be temporary, while you are using Firefox version 134.0.2, for example, because otherwise an automatic update would be done again, and the problem would reoccur.

Our team is still working on a permanent solution and we expect to have a first fix by tomorrow. We’ll keep you updated on any progress.

[bruce.alexander]

Please kindly provide an update here after you have released a fix. Thank you!

[marian.platonov]

Try please this alternative solution provided by the UiPath Product team for Firefox 135.0:

1. Download DriverExtensions_v25.2 and extract it anywhere on disk (e.g. D:\DriverExtensions_v25.2)
2. Run with Admin rights this PowerShell command:

&"D:\DriverExtensions_v25.2\SetupExtensions.exe" /firefox-policy-offline /silent

Or

cmd.exe with Admin rights:

"D:\DriverExtensions_v25.2\SetupExtensions.exe" /firefox-policy-offline /silent

Example:

This will upgrade the ChromeNativeMessaging.exe used by the Firefox extension and fix this issue.
No changes will be required to existing automation processes.

Note: We will include the fix in all LTS versions.

[patent-atanaka (Hiroaki Tanaka)]

I tried it, but the incident didn’t change. What’s wrong?

This extension works fine with Firefox v134.0.

[marian.platonov]

Raise a support case.

[patent-atanaka (Hiroaki Tanaka)]

I’ve raised the support case.

[Alan_Riquelmes]

I tried the solution, the extension recognizes the browser, but either way the result is the same.
Has anyone validated this solution?

[djz (Dzandstra)]

I have tried the solution to no avail. I get the same thing as @patent-atanaka

[marian.platonov]

We’ve worked with the UiPath Product team to develop a tested solution, and we’re happy to share it with you:

1. Download DriverExtensions_v25.2.zip and extract it anywhere on disk (e.g. D:\DriverExtensions_v25.2)

2. Run with Admin rights this PowerShell command:

&"D:\DriverExtensions_v25.2\SetupExtensions.exe" /firefox-policy-offline /silent

3. Set the environment variable UIPATH_ENABLE_FIREFOX_135_WORKAROUND with the value 1.

Run with Admin rights this PowerShell command:

[Environment]::SetEnvironmentVariable('UIPATH_ENABLE_FIREFOX_135_WORKAROUND', '1', 'Machine')

This will upgrade the ChromeNativeMessaging.exe used by the Firefox extension and fix this issue.
No changes will be required to existing automation processes.

Notes:

• We are planning in the future to test in advance the Firefox beta releases
• We will add the Firefox browser extension fix in the near future in the Studio/Robot and UiPath.UiAutomation.Activities.

[Alan_Riquelmes]

Thank you very much for the response, it works perfectly.

[patent-atanaka (Hiroaki Tanaka)]

@patent-atanaka

I tried it, but the incident didn’t change. What’s wrong?

I tried it too, but the incident didn’t change. What’s wrong? V134 Firefox is OK, but V135 is still wrong.

[marian.platonov]

Did you follow the exact steps from the new solution for Firefox 135.0?

[patent-atanaka (Hiroaki Tanaka)]

@marian.platonov

&“D:\DriverExtensions_v25.2\SetupExtensions.exe” /firefox-policy-offline /silent

The procedure is correct. I tried updating the project’s dependent libraries, but the problem persisted. I have no idea what the cause is, so I’ve attached the console log of the extension.
I’ve also uploaded same attachements to the support case.

FirefoxV135-UiPathWebAutomationNewest-console-export-2025-2-12_10-34-56.txt (2.0 KB)

[patent-atanaka (Hiroaki Tanaka)]

I found the cause. I missed the step of setting the environment variables. Now it works without any problems. And i have replied to the case that had been raised that it had been resolved and asked to close it.Thanks a lot.

[oscar]

Hi all, just reporting that I encountered this error with the Firefox extension as well in the latest Firefox ESR release. I am testing the fixes mentioned in this thread.

[oscar]

This fix seems to work. Unfortunately I am still having issues in Firefox ESR I think possibly as a result of the new changes.

But for now, this fix gets normal Firefox install working perfectly. Instead of installing the Firefox extension through Studio, just make sure to install it via this powershell method of “SetupExtensions” and it works!