Broken Admin Panel after clicking 'Clients'

[Rex]

Hi,

I'm experiencing the weirdest problem with PrestaShop.

I have been setting up my site for the last month, and it all worked great so-far. I don't have any sales yet, so all I have been doing is setting products and designing the site. Today I pressed the Clients-option in the menu in my admin panel, and the admin panel immediately broke. I can now not enter the admin panel anymore, although my frontend is still online.

I have turned on error reporting in define.inc.php and I see a small error, but I believe the error is unrelated to the broken adminpanel.

Warning: openssl_decrypt(): IV passed is only 7 bytes long, cipher expects an IV of precisely 16 bytes, padding with \0 in /home/autotune/classes/Rijndael.php on line 91

My nginx error log shows a bit more, but still nothing that worries me:

2018/09/03 18:56:23 [error] 23261#23261: *6953 FastCGI sent in stderr: "PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Warning:  openssl_encrypt(): IV passed is only 7 bytes long, cipher expects an IV of precisely 16 bytes, padding with \0 in /home/autotune/classes/Rijndael.php on line 52
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91
PHP message: PHP Notice:  Undefined index: submenu in /home/autotune/cache/smarty/compile/07/12/3e/07123e1c518d869f74b9b33944498ded858296b4.file.menu.tpl.php on line 91" while reading response header from upstream, client: 1.2.3.4, server: www.eurorecambios24.

I did notice one small weird thing in above's log. I see that the last line of the log is cut off for some reason. (weird. maybe it might be related?)

I'm running PrestaShop 1.6.1.20 and it's currently on PHP 5.6 (although it was running on PHP7.2 without problems before)

My website is www (dot) eurorecambios24 (dot) com, and the adminpanel can be found at /brokenadmin/

 

I'm kinda lost now and don't know where further to look. Anyone has any ideas?