login wp impossible

well i can access the sites:

www.foo.com and 
www.bar.com

but i cannot access the login – the sites are blank.

foo.com/wp-login.php
bar.com/wp-login.php

i have the following logs.

[Mon Jan 01 16:26:03.229924 2018] [core:notice] [pid 17589] AH00052: child pid 24869 exit signal Segmentation fault (11)
[Mon Jan 01 16:39:54.242584 2018] [core:notice] [pid 17589] AH00052: child pid 24872 exit signal Segmentation fault (11)
[Mon Jan 01 16:39:56.245833 2018] [core:notice] [pid 17589] AH00052: child pid 24870 exit signal Segmentation fault (11)
[Mon Jan 01 16:39:56.245959 2018] [core:notice] [pid 17589] AH00052: child pid 24871 exit signal Segmentation fault (11)
[Mon Jan 01 16:39:56.246014 2018] [core:notice] [pid 17589] AH00052: child pid 24873 exit signal Segmentation fault (11)
[Mon Jan 01 16:49:06.968278 2018] [core:notice] [pid 17589] AH00052: child pid 25032 exit signal Segmentation fault (11)
[Mon Jan 01 16:53:03.287697 2018] [core:notice] [pid 17589] AH00052: child pid 25034 exit signal Segmentation fault (11)
[Mon Jan 01 16:53:07.293645 2018] [core:notice] [pid 17589] AH00052: child pid 25039 exit signal Segmentation fault (11)
[Mon Jan 01 16:53:59.364044 2018] [core:notice] [pid 17589] AH00052: child pid 25106 exit signal Segmentation fault (11)

in other words – the admin-area is not acessible

what can i do: should i change the wp-login.php url to /login/
to get it to work: so all links in registration and forgot password emails have /login/ rather than wp-login.php.

You probably have a problem-causing plugin.

Look at the error.log file which will tell you the file that is causing the problem. Rename that plugin’s folder (use your hosting control panel’s File Manager) and retry. That should get you into the admin area. Then you can contact the plugin’s support forum to figure out the fix – or just delete the plugin.

Alternately, you can rename the entire plugin folder (in wp-content) so that all plugins are disabled, then move those plugin files individually by their folders to re-enable them.

But looking at the error.log file (via your hosting cPanel or via FTP program or hosting File Manager) will help you zero in on the problem.