This appears to be due to the issue reported at https://portal.smartertools.com/community/a93223/beta-7452-some-domains-cannot-load-after-update-from-previous-build.aspx 

For the next beta, we have added code that allows the json exception to propagate upwards to the interface if needed, so that a more specific error can be shown.  Please let us know if this problem happens in the future.

Hello Grady,

Thank you for your reply. 

Actually I'm not 100% sure it's related.

I've fixed the corrupt files from the other topic and all domains conversion seems now 100% ok.

I still have these toasters displaying though.

Kind regards.

Thanks.  We will consider this an active issue until we figure out what's going on with them.