error 500

Hello

Forgive my English, I will use google translator.

I have a wordpress version 4.4.7.

Today I went to enter the administration to update it and I have found that the administration part shows a 500 error.

I uploaded the files manually to upgrade to version 4.5 and it has been updated, but at the time of going to the administration, again the 500 error.

I have activated the error mode and I find a fatal error.

East:

Warning: Illegal string offset ‘remember’ in /home/ventalac/public_html/wp-includes/user.php on line 41

Warning: Cannot assign an empty string to a string offset in /home/ventalac/public_html/wp-includes/user.php on line 41

Warning: Illegal string offset ‘user_login’ in /home/ventalac/public_html/wp-includes/user.php on line 56

Fatal error: Uncaught Error: Cannot create references to/from string offsets in /home/ventalac/public_html/wp-includes/user.php:56 Stack trace: #0 /home/ventalac/public_html/wp-login.php(784): wp_signon(”, ”) #1 {main} thrown in /home/ventalac/public_html/wp-includes/user.php on line 56

Does anyone know what it can be and how to fix it?