That's not a TMS issue - you'd get the same error when putting that code directly into the template.

Try wrapping the code in <vb:literal></vb:literal>-Tags. The curly brackets are reserved characters, they're used in vB Template scripting.

Language phrase: $vbphrase_[processing_mode]
Reads in German: Durchzuführende Änderung
Should read as: (translated via Google): modification to be implemented

Can anyone tell me why when I try and edit an existing template modification through the TMS system that I get this error:

A Template-Mopdification with varname 'body_wrapper1' does already exist. Please choose a different varname.

Obviously the modification already exists, I'm trying to edit it.

Just to be sure. Version 1.2.0 is not to be used on 3.8.x forums, correct?

From the first post:
So: correct.

Are there any posts about this being made compatible for 4.2 over on the German forums?

It is working on my 4.2pl2 site.

No, since it's working with 4.2 just fine. What are your issues? Have you installed the patch for versions > 4.1.11?

After upgrading to 4.2, some of my styles are messed up. Images aren't loading, features missing. As soon as I disable TMS, things work perfectly. Since you said it's working, I can only guess that I have some PHP setting that's preventing it from working properly on my forum. Any ideas what it could be?

Going back over the thread, I made sure that gzip is only enabled once and I disabled output_buffering. Neither seemed to help.

It's very likely that your problem is not TMS, but the template changes themselves. You do realize that 4.2 has a completely new Nav Manager? All/most old changes you did to the navbar (probably via TMS) are deprecated and bound to break things.

As a general rule: TMS does not break the front end style, but the style changes you do via TMS might very well.