Forms are sent twice with Firefox

Issue

Using Firefox, some actions are triggering twice. For instance:

clicking on build with parameter for a job using a file parameter can trigger two builds.
uploading a plugin in the plugin manager results in it being uploaded twice (and the second upload failing).

Environment

CloudBees CI (CloudBees Core) on modern cloud platforms - Managed controller > 2.176.x
CloudBees CI (CloudBees Core) on modern cloud platforms - Operations Center > 2.176.x
CloudBees CI (CloudBees Core) on traditional platforms - Client controller > 2.176.x
CloudBees CI (CloudBees Core) on traditional platforms - Operations Center > 2.176.x
CloudBees Jenkins Enterprise - Managed controller > 2.176.x
CloudBees Jenkins Enterprise - Operations center > 2.176.x
CloudBees Jenkins X Distribution > 2.176.x
Jenkins LTS > 2.176.x
Using Firefox as a browser.

Resolution

This issue appeared in Jenkins 2.176.x and was fixed in 2.202 (weekly). The fix was back-ported in the upcoming 2.190.3 LTS.

Workaround

In case you are running an impacted version, the only known workaround is to use another browser.

References

This article is part of our Knowledge Base and is provided for guidance-based purposes only. The solutions or workarounds described here are not officially supported by CloudBees and may not be applicable in all environments. Use at your own discretion, and test changes in a safe environment before applying them to production systems.