I have an issue with the previews in Redactor 3.1.0-pl and it shows an error message:
Could not update preview, error thrown: [ReferenceError] $R is not defined
This may indicate an error in a plugin or Redactor itself. Saving your configuration and refreshing may resolve it as well. If the problem persists, please contact support with an export of your configuration and information about your browser.
It is occurring in all sets.
This may have happened during the upgrade from v3.0. I don’t remember this problem before upgrading and I don’t think I have looked in the Redactor settings since.
Possibly related to this topic which also showed up…