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Resolved Nginx error each hour (502) peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream

Lrnt

Basic Pleskian
Hi,

Sine a little time, I have an nginx error each hour (at HH:58:00) which result in a 502 Bad Gateway during 10-15 second.

I really don't know where it comes from?

Before turning of nginx, maybe someone will have an good idea?

Here is a the part of the nginx log when the error occurs:
Code:
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482905 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482905 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482909 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482911 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482913 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482915 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482917 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482919 connect() failed (111: Connection refused) while connecting to upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482921 connect() failed (111: Connection refused) while connecting to upstream                Erreur Nginx
2021-06-12 21:58:05    Error    XX.XXX.XXX.XXX        31293#0: *3482923 connect() failed (111: Connection refused) while connecting to upstream                Erreur Nginx
2021-06-12 21:58:10    Error    XX.XXX.XXX.XXX        31781#0: *3482927 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:10    Error    XX.XXX.XXX.XXX        31781#0: *3482929 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:10    Error    XX.XXX.XXX.XXX        31781#0: *3482931 connect() failed (111: Connection refused) while connecting to upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482933 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482933 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482933 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482937 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482941 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482943 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482948 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482950 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:14    Error    XX.XXX.XXX.XXX        32272#0: *3482952 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:19    Error    XX.XXX.XXX.XXX        300#0: *3482975 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:19    Error    XX.XXX.XXX.XXX        765#0: *3482977 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:19    Error    XX.XXX.XXX.XXX        765#0: *3482977 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:19    Error    XX.XXX.XXX.XXX        765#0: *3482980 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:19    Error    XX.XXX.XXX.XXX        765#0: *3482980 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:20    Error    XX.XXX.XXX.XXX        765#0: *3482987 upstream prematurely closed connection while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:23    Error    XX.XXX.XXX.XXX        1238#0: *3482991 recv() failed (104: Connection reset by peer) while reading response header from upstream                Erreur Nginx
2021-06-12 21:58:23    Error    XX.XXX.XXX.XXX        300#0: *3482975 peer closed connection in SSL handshake (104: Connection reset by peer) while SSL handshaking to upstream                Erreur Nginx
2021-06-12 21:58:23    Error    XX.XXX.XXX.XXX        1238#0: *3482993 connect() failed (111: Connection refused) while connecting to upstream                Erreur Nginx

  • The server is Debian 9.13
  • This website uses HTTPS Let's Encrypt Certificate
  • This website has a dedicated IP
  • This website has a "webapp" running on HTTP (Mandatory due to external hardware reachable through unsecure ws://)
  • Nginx has proxy mod enabled
I try to increase nginx buffer but it did not change anything (proxy_buffer_size 128k; proxy_buffers 4 256k; proxy_busy_buffers_size 256k; )
Thanks in advance for yours advices.
 
Wow ! Just found this in the crontab:
Code:
/opt/psa/admin/bin/php -dauto_prepend_file=sdk.php '/opt/psa/admin/plib/modules/sslit/scripts/keep-secured.php'
which is executed each hour at 58 MINUTES

Do you think 502 bad gateway errors come from that?
Is it safe to disable ? Or can I uninstall SSL It! and just keep Let's Encrypt! ?

Will my Let's Encrypt Certificates still be renew? (There also a cronjob "/opt/psa/admin/bin/php -dauto_prepend_file=sdk.php '/opt/psa/admin/plib/modules/letsencrypt/scripts/keep-secured.php'"

Thanks.
 
Note - I would have solution #2 in place anyways. Very few, if any, reasons not to use graceful restarts
 
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