Ok, so upgrading Certbot changed this error:
To this error:
That slight difference: stringEnd to string_end made all the difference.
A quick search for the new error code brought up this posting from a few years ago:
In that posting, the parsing error was attributed to commented out directives.
I suggest trying the following:
1- standardize all the comments - line the # up with the block indents and ensure there is one space after. e.g. # comment not #comment or # comment
2- if that doesn't work, try deleting the commented-out directives that span multiple lines first; then try the single lines
that should pinpoint what is causing the parsing error and allow you to file a bug report.