Magento - Error 500 - Internal Server Error

Question

I just finished with this whole website and all is working fine, I want to install french pack via ssh, I had problem with memory so I used root access to install and the installation was successful,

when I turned back to the website I couldn't access and I get this

Error 500 - Internal Server Error An error was encountered while processing your request. Typically this is a temporary condition. Please contact the web site owner for further assistance.

when I delete .htaccess I can access the front page only with no css, If I click on a link I got 404 Error

the module doesn't appear when I check modules status using

php bin/magento module:status

so I can't disable or delete it, even if I rename the vendor/imaginaerum folder nothing change

I also ran

find . -type d -exec chmod 500 {} \;
find . -type f -exec chmod 664 {} \;
chmod 777 -R downloader var media

to fix if any file permission but no result also

the French package I've installed http://imaginaerum.github.io/magento2-language-fr-fr/

Answer 1

The problem was that the Apache that he has has no module_version check and the <IfVersion> tags in the htaccess where not recognized. We temporarily removed them and he will see this with his host

EDIT :

After some more digging we installed mod_version on the apache and now it works

Answer 2

Most of 500 Errors are file permission issues.

I had this error before, the problem is in the files permissions.

Please follow this link to set the right permissions.

http://devdocs.magento.com/guides/v2.2/install-gde/prereq/file-system-perms.html

cd <your Magento install dir>
find var generated vendor pub/static pub/media app/etc -type f -exec chmod u+w {} \;
find var vendor generated pub/static pub/media app/etc -type d -exec chmod u+w {} \;
chmod u+x bin/magento

you can also try to execute upgrade command to see if there are any errors or missed PHP extensions

php bin/magento setup:upgrade

this also was answered in this question https://magento.stackexchange.com/a/219944/31830