Missing Lock File, cURL tls certificate error

P.S. If I switch to WP-CRON mode, the error message is pretty much the same…
29-Apr-21 15:25:37 ERROR Fatal error: forking process failed (cURL error 56: OpenSSL SSL_read: error:1409445C:SSL routines:ssl3_read_bytes:tlsv13 alert certificate required, errno 0: WP-CRON). Aborting

Can you try to edit this file: ninjascanner/lib/ajax_hooks.php

Search for:
'sslverify' => apply_filters( 'https_local_ssl_verify', false ),

There are 2 occurrences: line 93 and line 128.
Comment out or delete the two lines.

If that works, then I’ll add an option in the next version to disable SSL/TLS verification.

I commented out both lines, but still got the same result.
30-Apr-21 05:25:32 ERROR Fatal error: forking process failed (cURL error 56: OpenSSL SSL_read: error:1409445C:SSL routines:ssl3_read_bytes:tlsv13 alert certificate required, errno 0: AJAX API). Aborting

I guess that WordPress enables the SSL/TLS verification by default (which is a good thing).
Try to set it to false by replacing both lines with this one:
'sslverify' => false,

I still got the same result with that…
03-May-21 14:48:38 ERROR Fatal error: forking process failed (cURL error 56: OpenSSL SSL_read: error:1409445C:SSL routines:ssl3_read_bytes:tlsv13 alert certificate required, errno 0: AJAX API). Aborting

But, I figured it out. I have CloudFlare on the site with the problem, and I have “Authenticated Origin Pulls” enabled. When I disabled Authenticated Origin Pulls in my server configuration and paused CloudFlare, it started working. Just pausing CloudFlare alone did not fix it.

So I am assuming the problem is happening because the server can’t do a simple loopback when Authenticated Origin Pulls is on.

I’m research if there is a fix for this. But at this point, it does not look like it is a NinjaScanner problem. So I’m marking this as resolved. Any more ideas would be appreciated though.