Issue is in your Profile Create a new profile as a test to check if your current profile is causing the problem.

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem. Never work with original files.

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

There is another way but is more of a work around and does not fix the Profile Issue.

Please let us know if this solved your issue or if need further assistance.

Catbug said

a lot of adds-on tells me stuff like "This add-on requires a newer version of Firefox (at least version 56.0). You are using Firefox 49.0." but im up to date running Version 57.0.2 (64-bit). is it the add problem or is there a problem with my browser?

In your more system details on right your useragent shows as Mozilla/5.0 (X11; NetBSD amd64; rv:49.0) Gecko/20100101 Firefox/49.0

https://support.mozilla.org/en-US/kb/how-reset-default-user-agent-firefox

Fix it! Thank you all such much c: