It seems something is wrong with the server itself...
CloudyHamster42 what's the trains-server version ?
where is it running? could you restart all the dockers ? Is it running on your machine?
hit ctrl-f5 (reload the page) do you still ge the same error? Is it limited to a specific experiment?
its also having trouble saving things to the server it seems
not limited to a specific case and also happens after reloading the page