Failed updating index template when updating to 7.8

Hi!

Recently we updated the stack from 7.5 to 7.8 and everything went smooth. However today we tried to update our index template through Kibana's ui and when saving the changes we got the following message.

If I recreate the template the message doesn't appear and the template is created. Is this behaviour expected?

Thanks!

Welcome to our community! :smiley:

What did and does the template look like?