Error while updating config

[axcl]

Plugin Version: email-notifier-1.0.0-74.jar
GoCD Version: 21.2.0

Whenever i tries to change config it throws following error

Someone has modified the entity. Please update your copy with the changes and try again.

I have also tried completing removing and adding plugin again but somehow config still stucked.

[chadlwilson]

Dupe of gocd/gocd#9405