Denis, I am assigning this to you since you had just fixed a similar issue (10860).
Please let me know if you need any additional information.

I couldn't update the "I will donate to the project if issue is resolved" setting but I will donate once this was fixed.

Donate to me ?

Not same issue, then remove the link. It's surely a bug between JS regexp and PHP regexp

regexMatch('/^[0-9]{5}$/',Validation2_03) work

I can either donate to the project or to you or both, whatever you prefer.

Thanks for providing the additional regex. I really wonder why that makes a difference...?!

Unknown modifier ']'

http://www.sondages.pro/brouillon/

You're regexp have an issue an / must be preceded by \

But this must be shown in Validate EM

OK :

in PHP : try reg_match($pattern.'u', $input); then "/.../.../" return false
in JS : reg = new RegExp(pattern.substr(1,pattern.length-2));

Then remove first / and last /

2 fix to do :

• Add the pattern error in Validate logic
• return false if there are an issue with pattern before removing the / .

PS: Uploaded fixed lss file.

1st part : show the error : https://github.com/LimeSurvey/LimeSurvey/pull/475

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=18522

Fix committed to 2.06lts branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=18523

Wont fix the JS/PHP difference actually.

Version 2.50+ Build 160415 released