wordpress is writing incorrect htaccess when i'm trying to connect to wp-admin

Hi everyone,

So here is my problem.

When i’m trying to enter in one of my sub-site admin, wordpress is changing my htaccess, and after that, i’ve got an internal server error on all my multisite installation. This behaviour was caused by trying to change the permalink structure for that sub-site.

If i come back to the old permalink structure by manually changing the htaccess, i can access the other sub-sites (front and admin), but everytime i try to access problematicsubsite/wp-admin, wp is writing a wrong htaccess again. Below is the wrong htaccess wp is writing.

Thnaks for your help.

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]# BEGIN WordPress
ErrorDocument 404 /index.php?error=404
# END WordPress
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]