An error occurred while saving the commentSteve commented
Workaround (but not ideal) - Return to Classic, then Focus on Content.
6,325 votesworking on it · AdminSharePoint UserVoice Admin (SharePoint UserVoice Admin, Microsoft SharePoint) responded
Providing a consistent user experience across M365 that continues to function as expected is a very complex problem which we have been validating in a Private Preview Program.
The good news is that we are once again able to accept additional nominations into the Private Preview. If you would like to nominate yourself you can do so at https://aka.ms/SPOTenantRenameNomination. Please note that a nomination does not necessarily mean that you will be accepted. We are reviewing these on a case by case basis and will only be in contact if accepted.
For more information about renaming your SharePoint domain including the current limitations and process visit https://aka.ms/SPOTenantRename.