Why can't I view or edit Umbraco templates?

Question

When I open the Umbraco (7.6.3) backoffice, I'm unable to view or make changes to templates. It seems like other functionality is unaffected, and I can create & edit specific pages. However, attempting to open the templates themselves just leads to a white screen. This problem exists across browsers:

Other screens render just fine:

What gives?

Checking the console when attempting to load gives an interesting error:

Error: Argument 'Umbraco.Editors.Templates.EditController' is not a function, got undefined...

---

Resolution:

The issue seemed to be caused by outdated files in the Umbraco folder. Copying most directories over from packages\UmbracoCms.7.6.3\UmbracoFiles\umbraco\ seems to have done the trick.
Looking at the changelog, it seems like the JS folder was the most influential in getting this fixed.

Answer 1

Are you sure that you're on 7.6.3? The UI appears to be pre-7.6 (I can tell because the colours haven't been updated).

If you have just upgraded, it's possible that your browser has cached the JS which is used - hard refresh your browser to see if the UI updates.

Umbraco also uses a dependency service to compile all of the used JS/CSS files together into one large one. This service will not be used if your website is in debug mode. Either:

• Turn debug mode on in the Web.config
• Delete any files in the \App_Data\ClientDependency\ folder as this is where the cached compiled files are kept (these will be regenerated)