Ok, thank you for your involvement in my problem.

Is there any news? Is it a common error or this problem occurs only at my machine?

Thank you

System is 64bit, PyFMI and FMlob were installed through conda and worked on the older version of openmodelica. Both the new and the old versions of openmodelcia are 64 bit. The old one was downloaded 28th of may 2018, the newer is 15th of october

Oh, sorry, was unclear.
It's windows. By decoding FMU I mean creation of model in python through pyFMI

After I reinstalled OpenModelica to a newer nigtly build - I get the following error, decoding it's fmu's: UnicodeDecodeError: 'utf-8' codec can't decode byte 0xcd in position 24: invalid continuation byte
Previous versions worked properly.
Problem is not in a model, as even the simlest testing models give the same results.
How can I fix it?