"Add Source" in Branches Sources under Configure not responding

Jenkins setup: [Jenkins 2.277.4]

HI,

we updated Jenkins from 2.263.4 to 2.277.4 and also subversion from 2.12 to 2.14.
the issue that we are facing now is that we can not open the drop down list button once we create a new pipeline and configure it. (


)
the button is not responding. i can click on it and the list is shown but once i select one of the versioning tool like subversion or git the button is still show “Add source”. so there is no possibility to connect jenkins with our repository.

We initially start the upgrade from the version 2.178 and the button is working until the version 2.263.4.
On 2.839.3 the issue is also present.

Can you please help

Thanks

Sorry but 2.277.x is over 4 years old. I doubt anyone is willing to look into such old code.
You should try to update to a recent LTS 2.479.x or 2.492.x, if the problem persists, then you can come back.