I assume you know 8.5 is about 3 years old now but in case you don’t I recommend you download the latest and use that.
Having said that a couple things to check:
Does Komodo know it’s an HTML5 file? It looks like it from the error but who knows. Top right of the status bar in Komodo 10. Bottom right of the status bar in Komodo 8.
Check your prefs: Edit > Preferences > Syntax Checking > select HTML5 form the language dropdown.
Yes, I do know it is three years old. I have been checking for updates, and it tells me that I have the latest version. I assumed that it was just abandoned in favor of the paid IDE. Thanks for pointing that out to me, so I will manually download a new version, and follow-up here.
Not at all. We’ve never supported auto-upgrades from one major version to another. Way too much changes to make that a consistently pleasant experience. Komodo Edit gets developed along side Komodo IDE. Glad I could clear that up for you!
Hopefully we can get your syntax checking issue sorted just as quickly.