Forum error when attempting to edit post

I encountered an error I used to encounter quite frequently on an older version of the forum when trying to edit the content of a post.

After trying to save the comment, I received the following error:

Attempt to assign property "FormatBody" on bool.

This appears to suggest that a string or other text value is attempting to be saved to a boolean variable somewhere in the code. As far as I can interpret this error message, anyway.

The post in question did contain a quote, if that affects it in any way.