I've got PRTG running on Server 2016.

Both core and probe service run on this box. Core is running fine and the web interfaces launches etc.

On the 15th the core and probe service restarted (for no obvious reason? This is something that happens occasionally, I don't think it was an update and the server itself didn't restart).

Anyway, after the core service successfully started I just get the following from the Probe service:

Error		15/05/2018 12:13:12	PRTGProbeService	0	None  
                Service failed on start: Access violation at address 00B6878C in module 'PRTG Probe.exe'. Read of address 00000074
Error		15/05/2018 12:13:12	PRTGProbeService	0	None
                Can not start probe: Could not load SSL library.

This continues after rebooting the server itself.

Looking into it a bit further the restart on the 15th indicated 5 days uptime. The last Windows update was installed on the 10th so I'm guessing something there has caused me problems, however the patch notes don't offer anything obvious that might be causing the problem.

Any thoughts on how best to proceed?

Article Comments

Hi there,

The PRTG service might got updated. To avoid any issues with third party tools or antivirus systems please install the latest update from PRTG manually again. To manually update your core server, download the installer from the following URL and install it on top of your currently installed version:

Please note that monitoring will be disrupted for a few minutes during the update, remote probes (if any) will automatically be updated after the core server is updated.

Does the issue persist afterwards?

Best regards.


May, 2018 - Permalink

Great, thank you thats working again. I was hoping to avoid a re-install but if i'd realised it was that straight forward I'd have just got on with it!

Thanks for your help.


May, 2018 - Permalink

Since last reboot I get this error message:

Ticket #173: Caution! Your monitoring is interrupted because the core server cannot accept incoming probe connections

Opened by PRTG System Administrator Latest Comments: Your monitoring is interrupted until this issue is resolved: Could not load key, check password. error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch

Tried to reinstall, no success.


Jul, 2018 - Permalink

Hi there,

Do you use any custom certificates for PRTG? Please check that all files are available in the "C:\Program Files (x86)\PRTG Network Monitor\cert\"-folder:

  • dh.pem
  • openssl.cnf
  • prtg.crt
  • prtg.key
  • root.pem

    Best regards.

Jul, 2018 - Permalink

I'm also suddenly getting this one: Caution! Your monitoring is interrupted because the core server cannot accept incoming probe connections


Feb, 2019 - Permalink

Hi there,

Please check the settings under "Setup > System Administration > Core & Probes" to make sure that PRTG allows Probe Connections.

Best regards


Feb, 2019 - Permalink