myxiplx

Right, that answers it. If you're getting that error then either you copied the default folder when creating your custom UI, or the custom UI you included uses a custom SIDL.xml file.

If you copied default then this can be solved by deleting SIDL.xml. Unfortunately, it also means you're likely to have a whole load of other out of date files in there. That is why copying the default is bad, since it's likely you'll now need to work out which files were from default and remove them all so that EQ can load the correct, up to date files.

Alternatively, if the UI includes a SIDL.xml file then it's almost as tricky. You can try removing it, but there's a good chance you'll loose some functionality or get more errors after doing that. UIerrors.txt only generally shows one error at once, so it's going to be a case of fixing one problem, and seeing what crops up next.

To be honest, unless you know quite a bit about UI's and interpreting the UIerrors.txt file, you're probably better starting again. Create a new (empty) folder under uifiles, download the pieces you want again, and save just the files from the downloads in there.