I am using this new free version of lite-c along with Gamestudio that was uploaded recentily. It says SED version 7.35.0.

I imported fully working program from the previous free version of Lite-C into the new one and now I have some trouble. In one place, ptr_for_handle() returns pointer different than the one handle() was called for earlier. This then naturally causes a crash.

What can I do with this?

Simply put, it is most probably of a non-valid handle.
Maybe, a bug already had been in the code before and it already was only by luck that you had no problems before, or you changed more than you remember within the code after importing.
Test the validity of the handle!
Is there still the file?
How did you store the handle?
Did you store it within a skill, is the skill used more than once?
Is the pointer valid?
Or did you insert a wait after ptr_for_handle, and before using that pointer?

Does it simply crash, or do you get an error message?