Unable to create pages in WorPress 5.4 with Gutenberg

[ysintos]

Hello, after installing a clean WordPress 5.4 with Gutenberg only, and not classic editor in a OLS 1.6.10 server and i try to create a new page or post, i get the error "Unable to create post. The response is not a valid JSON response".
After installing the Classic Editor, everything is working fine. I can then create posts and pages normally with classic editor and with block editor.
You think it might be a Wordpress or an OLS issue ?

Thank you

 

[Pong]

You can check the error log to see if it triggered mod_security rule or not, you can disable that particular rule to avoid error.