If you cant post new blog posts or save edits to your newly installed expression engine blog. Here is the fix that worked for me.

I installed EE for the first time, version 5.3.0… the install went perfect. the permissions were set correctly. but I could not post a new blog post or save edited posts… turned out ModSecurity is an Apache mod on the server that was blocking my IP… so the fix was to call the hosting company and have them remove my blocked IP. now everything works fine. wanted to share this with others having similar issues. 😊 hope this is helpful to someone…