Background of the issue:
I am trying to rebuild my website after disabling and removing most plugins due to a huge error. I reinstalled and activated the WPML plugins. The issue can be seen at: hidden link.
Symptoms:
After reinstalling and activating the WPML plugins, I get a big error on top of my pages. The error message includes multiple 'Deprecated' warnings related to implicitly marking parameters as nullable, and 'Warning: Cannot modify header information'. These errors appeared after WordPress core was automatically updated to version 6.8.3.
Questions:
What is causing the deprecated warnings and header modification warnings?
Is this an error on your side or is there another problem?