I updated to 5.7.5 on a client site and I am unable to save any post updates. In the console I see
POST https://example.com/wp-admin/admin-ajax.php 400 ()
POST https://example.com/wp-admin/post.php 500 ()
Disabling ACF Pro ended the issue. I don’t see anything in PHP logs. I downgraded to 5.7.4 and enabled the plugin and the issue disappeared.
I am running the latest version of ACF and not seeing these issues.
Make sure you clear your browser cache, it could be that you’re loading an incorrect JS file.
Past that you’d need to give more details because you have not included enough to understand what the errors are.
