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"EOF was observed that violates the protocol" on start up



I get the above message when I try to start PRTG Network Monitor using the regular icon (PRTG GUI Starter.exe). It also says "Error connecting with SSL". If I manually browse to URL it works ok. I don't see any errors in the web server log but the core server seems to think there is a conflict on port 80/443. I don't see anything else running on port 443 and the server is configured to use HTTPS, so I don't know why port 80 would matter. I am running version

It was running fine for a long time so I don't know what happened. I upgraded not long ago but it continued to work ok until now.

Any ideas? I might try another upgrade to see if it resolves it.

eof ssl web

Created on Jan 15, 2019 12:07:38 AM

2 Replies



Hi there,

You don't need the "GUI Starter". This is just a shortlink to the webinterface of PRTG. Therefore please continue to reach PRTG via your browser, via the Enterprise Console or the Desktop Client:

Best regards.

Created on Jan 15, 2019 11:46:53 AM by  Dariusz Gorka [Paessler Support]



This happened to me when I removed TLS 1.0 from accepted SSL protocols on the PRTG server. So, that is why you are getting the protocol error. Not a big deal, just hit the webpage.


Created on Apr 30, 2019 12:19:13 PM

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