ValueError when converting a repository from Mercurial to Git. What could be the problem?

Question

git

I have been using Mercurial for a very long time, as have my colleagues. Without external access via the Internet. And then we decided to switch to Git. I'll explain why. There is of course a BitBucket option. It supports both options. But he has limits on the size of the team. And then pay. And I would like to keep the project closed and hosted on GitLab. There like it is possible to create the closed projects.
Mercurial client on TortoiseHG. They also chose a very long time for various parameters.
Now to the issue of conversion. Tried different tools. According to the instructions from git-scm, I used the "hg-fast-export" tool. But unfortunately nothing happened. Although I did everything according to the instructions. The conversion didn't happen.
But TortoiseHG has a "hggit" extension. I tried to use it. Not so big and complex projects are converted without problems.
But here something goes wrong and there is such an error:

Who faced a similar problem and how did you solve it?