This incident has been resolved.

We plan to release a fix this evening that will solve the issue with rich content blocks in groups/dashboards that some of our customers have experienced. We have decided to do the roll out this evening to avoid any risk during peak hours. We are sorry for the problems caused.

The issue has been identified and a fix is being implemented.

Some customers may experience an error when trying to add a rich text content block on dashboards/groups.
We are working on a fix for this issue.