error403 because of _wpnonce

When i’m on the page that list the themes (themes.php) i have no problem
When i select one theme between three ; i have the error : error 403 permission denied

The rights of the files are good otherwise i could not list the themes on the page themes.php

After several tests, it seems that comes from _wpnonce on the URL

example, this produces the error403
themes.php?action=activate&template=clear-line&stylesheet=clear-line&_wpnonce=7f495c430e

this does not produces the error403 but does not do the update (it’s normal:) )
themes.php?action=activate&template=clear-line&stylesheet=clear-line

For some other themes i’ve choosen, _wpnonce change and then i can activate theme but not the one i want.

I’ve the same behavior with the spam management:

– If i select all the for deletion => error 403
– If I delete them one by one => no error

Any suggestion ?

Regards.