Intermittent SSL connection errors with HTTP requests

Development Programming & Scripting Multiplayer & Networking
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1

Hello there!

Some of our users are reporting issues surrounding features that make HTTP calls to our own servers. After receiving their logs, we noticed that some users are getting:

[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: request failed, libcurl error: 35 (SSL connect error)
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 0 ( Trying [redacted]:443...)
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 1 (Connected to uas-auth.mypethooligan.workers.dev (redacted IPv6) port 443)
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 2 (ALPN: curl offers http/1.1)
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 3 (TLSv1.3 (OUT), TLS handshake, Client hello (1):)
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 4 (Recv failure: Connection was reset)
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 5 (OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to redacted:443 )
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 6 (Closing connection)
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 7 (Recv failure: Connection was reset)
[2025.10.10-17.17.19:671][985]LogHttp: Warning: 0000019CBD8A19D0: libcurl info message cache 8 (Recv failure: Connection was reset)

In addition to the connection reset error, we also have gotten reports of similar yet different logs:

[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: request failed, libcurl error: 28 (Timeout was reached)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 0 (Found bundle for host: 0x2be0e7ff790 [serially])
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 1 (Connection #2 isn't open enough, can't reuse)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 2 (Connection #3 isn't open enough, can't reuse)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 3 (Connection #4 isn't open enough, can't reuse)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 4 (Hostname redacted.playfabapi.com was found in DNS cache)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 5 ( Trying 20.42.182.110:443...)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 6 (Connected to redacted.playfabapi.com (20.42.182.110) port 443)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 7 (ALPN: curl offers http/1.1)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 8 (SSL reusing session ID)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 9 (TLSv1.3 (OUT), TLS handshake, Client hello (1):)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 10 (TLSv1.3 (IN), TLS handshake, Server hello (2):)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 11 (TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 12 (TLSv1.3 (OUT), TLS handshake, Client hello (1):)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 13 (SSL connection timeout)
[2025.10.09-18.38.30:137][893]LogHttp: Warning: 000002BF3DE698D0: libcurl info message cache 14 (Closing connection)

So far we haven’t been able to reproduce the issue, any help here is appreciated.

Best,

Charles

2

Steps to Reproduce
N/A

3

Is this an intermittent problem? From the logs, it looks like general connectivity issues during the ssl handshake, based on the “Recv failure: Connection was reset” and “SSL connection timeout” messages.

4

Yes, we’ve had it be resolved by restarting the game but other users have reported it’s happening every time for them so the game is left in a broken state for those players. I’m not sure if there’s any way on the config side to fix this or if it’s only fixable at the end user’s machine (update Windows certificates, allow UE through firewall + anti-virus etc). Thanks for your help.

5

In the case where it’s fixable by updating Windows certificates, you could ship that missing root certificate with your game. UE will load “/YourProject/Content/Certificates/cacert.pem” and utilize that when making https requests.

6

So your guess is that the game is just packaging a different version of the cert than some of our users have on their machines which cause the failures? I’ve asked the folks who are having the issue to update Windows to see if it resolves it.

7

One of the users updated Windows and is having the same issue. I am requesting their logs to confirm that it’s still a problem with the SSL cert.

8

Including an updated cert would only fix the scenario where updating the windows certificates fixed it for the user. I do not expect that is the case for the logs you shared, which just look like general connectivity issues for those users.