404 page not found when debug mode "True" and whith textarea field

[Alexis]

Hello the community,

1st bug: on a textarea field called "body", if i insert a table or an image in this field, i will get the "404 page not found" page after saving the page and no modification is saved.
             The same bug happens wether i use plain text, tynyMCE or CKEditor or with a brand new textarea field.

2nd bug: when i am in the debug mode ($config->debug = true;), i get the "404 page not found" page instead of the homepage. All other urls works fine.

The site is 10 years ols and has been updated with the ultimate version of PW (3.0.243) and modules but still the same bugs.
I'm not sure if the 2 bugs are related or not.

Anyone has an idea in which direction i should look for the origin of the bugs?

Thanks.

Alexis