I am currently setting up a Website with Worpress but i cant update the pages because of this error.
I am a total newbie when it comes to wordpress/ programming etc and dont know much of the deep dive things i could try or do.

I have tried everything what i could find in the net..
Plugins – X
HTTPS -X
Themes -X
HTACCESS -X
Permalinks – X

putting this piece of code in the htaccess:

<IfModule mod_security.c>
SecRuleEngine Off
SecFilterInheritance Off
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>                               - X

putting this in Config.php:

/* Add any custom values between this line and the “stop editing” line. /
/ enable Debug mode */

`define ( 'WP_DEBUG', true);
define ( 'WP_DEBUG_LOG', true);     

                       -- X 

cleaning cache – X

DEBUG LOG gives me this:

[03-Jun-2024 08:50:43 UTC] Cron reschedule event error for hook: wpseo_indexable_index_batch, Error code: invalid_schedule, Error message: Event schedule does not exist., Data: {"schedule":"fifteen_minutes","args":[],"interval":900} – i did check cron jobs with plugin but to my uneducated eye it looks fine, nothing that should cause this problem i guess.

I am just working on my Work PC with windows- Nothing speacial installed

The one thing i did not try because i dont quite understand is rest API. There is also an error when i want to visit the wp-json site it shows an error “not found -The requested URL was not found on this server.”

other than that i can’t find anything that works to solve this Json error..

Note: My Hoster is Telekom ..it is what my boss wanted

I also have the website report in hand