if you can't switch from popup to inline editor, your installation has a deeper problem, hard to say what.

Dear Luis...

We have try to solve the problem above mentioned without results...
We have built
- new server win2012 (no others applications installed)
- installed your package version limesurvey2.65.6+170615 download from site - installated without problem
- no plugin or other programs installed

When we try to access the editor in INLINE mode is all OK (see image 1)
When we try to access the editor in HTML mode is all OK (see image 2)
When we try to access the editor in POPUP mode A ERROR APPEAR (see image 3)
The error appear again..... also in a new free installation

Seems that the path will be not correctly built..
limesurvey-stg.valoreformazione.it/index...description_it/text/ [Descrizione:](it)/type/survey-desc/action/editsurveylocalesettings/sid/765575/gid/0/qid/0/lang/it

If I cancel "[Descrizione:](it)/" from path a new page with editor is open....

Note that the installation is clean and you can reply the situation quickly... I can give you access to admin panel to check the problem.
In our installation the same problem is present also with LINUX environment....

Can you check and give us some info about?
Beste regards

Sorry, I've forgotten the image
Bye

I think there are an issue about a new security system. I take a look and fix it , sending the update here.

Fix to be apply : github.com/LimeSurvey/LimeSurvey/commit/...72b823cb3eb9eace4631