I have just finished setting up a Tor relay and am using nyx for monitoring. I am constantly being warned about the following error:

Nov 29 20:49:54.000 [warn] TLS error: internal error (in SSL routines:tls13_hkdf_expand:---)
Nov 29 20:50:04.000 [warn] Unhandled OpenSSL errors found at ../src/common/buffers_tls.c:155:
Nov 29 20:50:04.000 [warn] TLS error: internal error (in SSL routines:tls13_hkdf_expand:---)

Is that something to be concerned about... and anyway why is this happening?

2 Answers 2


I have the same error since upgrade from openssl to version openssl-1.1.1.a-1 on linux arch. Downgrading openssl to version openssl-1.1.1-1 solved the problem.

  • yeah bruh... helped in my case too Kudos! Commented Dec 7, 2018 at 8:41
  • Same error with 1.1.1a and Tor on CentOS 7.6.
    – drew010
    Commented Dec 16, 2018 at 6:04

Due to regression introduced in OpenSSL 1.1.1a. Openssl says fix in next openssl release: https://github.com/openssl/openssl/issues/7712

Until then, workaround for coping with OpenSSL 1.1.1a added to Tor: https://trac.torproject.org/projects/tor/ticket/28616

Can confirm that Tor no longer issues these errors. Look for this in the Tor log:

[warn] Detected OpenSSL bug 7712: disabling TLS 1.3 on future connections. A fix is expected to appear in OpenSSL 1.1.1b.

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