From what can see in what you posted, you are using Version=55.0.2

https://support.mozilla.org/en-US/kb/update-firefox-latest-version?cache=no Did you update Firefox to the latest version 55.0.3

Unfortunately I can't update Firefox internal because I can't start firefox. The package manager brought me 55.0.2 with the reinstall via apt-get. But no change with the crashes.

If you have trouble with the upgrade, use this link; http://www.mozilla.org/en-US/firefox/all/

No effect using firefox 55.0.3. I also tested midori as a secound browser next to firefox --> midori works fine.

Firefox v55 has been having problems with graphics drivers and protection programs.

Check out Firefox v56 beta, some of the issues with Intel drivers have been fixed. https://www.mozilla.org/en-US/firefox/beta/all/

Note: v55 has been giving users problems. Reinstall v54.

https://support.mozilla.org/en-US/kb/install-older-version-of-firefox?cache=no Be sure to read everything here.

If you still want to downgrade, look under; I still want to downgrade. Click the Directory of other versions and languages link. Look for the directory of the version that you want. But, remember that old versions may have security issues.

You should also check out Firefox; Extended Support Release {web link} ESR Notes System Requirements

Today I installed 54.0.1 but the problem already exists. I also looked for other data from firefox on my file system (I followed this guidence https://askubuntu.com/questions/16758/removing-firefox-in-ubuntu-with-all-add-ons-like-it-never-existed) but I only found firefox files in one directory (~/.mozilla) after 'apt-get purge firefox'.

A test of v56 beta will follow today in the afternoon.

Without building a own on, I tested v52.0.2 which was build for ubuntu16.04 (my ArmBian in use based on ubuntu16.04). --> It works fine! But I have absolut no idea which effect crashs the other versions.

As long as it works. Maybe someone else knows what's going on.