We look in to redmine production.log file an see follow error

git: error during get default branch: Couldn’t find all GitCaches with ‘id’: (last, {:order=>”created_at DESC”}) (found 0 results, but was looking for 2)
Completed 404 Not Found in 361ms (ActiveRecord: 66.9ms)

What can i do to fix this issue?

Gitolite upgrades can change /home/git/.gitolite.rc this file.

Than can happend, that you have a UMASK 0077 thats wrong, you need 0022

Thats all

Edit:

Another Solution is

setfacl -R -m u:git:rX /home/git/repositories/

Hint found here

http://www.fabianfier.de/blog1.php/redmine-shows-404-error-on

https://stackoverflow.com/questions/7086325/setting-umask-in-git-gitolite