TexStudio: Biber claims biblatex version is wrong

Okay, the issue was an outdated biblatex version. According to the Biber doc you need Biblatex v3.2 to work with Biber v2.3. Unless you don't have these versions it's not going to work.

And Biblatex v3.2 creates a .bcf file with the version number 2.9:

<?xml version="1.0" encoding="UTF-8"?>
<bcf:controlfile version="2.9" xmlns:bcf="https://sourceforge.net/projects/biblatex">

Basically I solved my problem by just reinstalling MiKTeX. You can also use the package manager to install the latest packages, but in my case it created just more problems.

I have MikTeX 2.9 installed on Windows 10. All packages are updated (in Admin as well as in User mode). When I tried to used Biber I got an error message:

INFO - This is Biber 2.7
INFO - Logfile is 'main.blg'
INFO - Reading 'main.bcf'
ERROR - Error: Found biblatex control file version 2.9, expected version 3.3.
        This means that your biber (2.7) and biblatex () versions are incompatible.
        See compat matrix in biblatex or biber PDF documentation.
INFO - ERRORS: 1

In package manager the following versions were shown:

• 2.7 for miktex-biber-bin-x64
• 3.7 for biblatex

Reinstallation of these packages did not solve the problem.

I checked which biblatex file is used in the system with the following command (open cmd window and simply type this)

kpsewhich biblatex.sty

The output was:

C:/Users/xxx/AppData/Roaming/MiKTeX/2.9/tex/latex/biblatex/biblatex.sty

Folder C:/Users/xxx/AppData/Roaming/MiKTeX/2.9/ is basically used to install packages installed "on the fly".

I searched if there are other files biblatex.sty in the system and it turned out that the second copy was stored in the MikTeX installation folder:

c:\Program Files\MiKTeX 2.9\tex\latex\biblatex\

I am not sure what it means. Is it that my MikTeX installation is corrupted or I have double installation of biblatex nor what is the reason for all this.

I made a simple test. I change the folder C:/Users/xxx/AppData/Roaming/MiKTeX/2.9/tex/latex/biblatex/ name to C:/Users/xxx/AppData/Roaming/MiKTeX/2.9/tex/latex/biblatex_old/

and copy the whole folder from c:\Program Files\MiKTeX 2.9\tex\latex\biblatex\ to C:/Users/xxx/AppData/Roaming/MiKTeX/2.9/tex/latex/biblatex/

Next I cleared all generated files in my tex project folder (it is important) i.e. delete *.aux, delete *.bcf, ... etc. and recompiled the project again with pdflatex, next biber, next pdflatex

It works!