I've had a suggestion of deleting the App_Data/TEMP folder and restarting the environment for an issue I'm having with an Umbraco Cloud project (a restart happened at the sometime someone was updating a doc type in the live environment, which has caused the doc type to go a little wonky) I don't really know what the folder is used for, and just wondering if there's any problem with removing it?

It holds temp data, so Umbracos cache, search indexes, fileuploads (until they are stored in a persisted location), etc. Some packages may also place things there. As a rule of thumb only things in there are things that should be rebuildable, a standard Umbraco install will pick up on missing things during startup and regenerate them

We remove it automatically on every deploy using the "remove additional files at destination" deployment option. Never had any problems

thanks that's real useful, appreciate it