SandboxDataException error message on Chatter
|Knowledge Article Number||000193817|
When accessing the Chatter tab or creating/editing Chatter groups in a Sandbox, you might receive an error similar to the following
This usually happens because of a problem during the sandbox copy process. The copy process does not take a snapshot of your production org, rather, it copies whatever is in there. This can sometimes cause issues where we reference something that no longer exists. When this happens, the above error might occur. At this point the only available workaround is to refresh the sandbox, and create a new copy.