Hiya,

So I've enabled Questie in the addons menu and ticked load out of date addons, it's in the addons folder and all requirements are checked. However every time I log on I get the error message seen in the attached picture. I've relentlesly searched the internet for a fix but can't find anything. After I close the error message, nothing shows on my screen or the map screen to do with questie.
Not sure how to fix this?

Check the FAQ point 21.

You're trying to run an updated version of Questie on a private server. Since a lot of updates Questie is for Classic only and not supporting private servers anymore. However you can grab v3.7.1 which is the last Questie version for 1.12.