Problems on Installing Gitlab postgresql::enable line 196

Hey out there, I need help.

I tried to install Gitlab on a fresh Version von Ubuntu 18.04 on Strato (Hosting Provider).
I installed step by step like this tutorial does: https://www.howtoforge.com/tutorial/how-to-install-and-configure-gitlab-on-ubuntu-1804/ , but I’m getting an Error on gitlab-ctl reconfigure:

Error
   System Info:
------------
chef_version=13.6.4
platform=ubuntu
platform_version=18.04
ruby=ruby 2.5.3p105 (2018-10-18 revision 65156) [x86_64-linux]
program_name=/opt/gitlab/embedded/bin/chef-client
executable=/opt/gitlab/embedded/bin/chef-client


Running handlers:
There was an error running gitlab-ctl reconfigure:

postgresql_user[gitlab] (postgresql::enable line 196) had an error: Mixlib::ShellOut::ShellCommandFailed: execute[create gitlab postgresql user] (/opt/gitlab/embedded/cookbooks/cache/cookbooks/postgresql/resources/user.rb line 11) had an error: Mixlib::ShellOut::ShellCommandFailed: Expected process to exit with [0], but received '2'
---- Begin output of /opt/gitlab/bin/gitlab-psql -d template1 -c "CREATE USER \"gitlab\"" ----
STDOUT: 
STDERR: psql: could not fork new process for connection: Resource temporarily unavailable

could not fork new process for connection: Resource temporarily unavailable
---- End output of /opt/gitlab/bin/gitlab-psql -d template1 -c "CREATE USER \"gitlab\"" ----
Ran /opt/gitlab/bin/gitlab-psql -d template1 -c "CREATE USER \"gitlab\"" returned 2

Could you please explain me, how to fix this error?

Ok… One Night later… the System is Working now… Nice… I didn’t do anything.

But thanks for your help! Maybe a Problem with not enough Ressources on my VServer.