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Failed to establish secure connection: Socket Error # 11002 - IOHandler value is not valid



Sometimes I get the following message in PRTG with some website I want to monitor. Does anyone know what this message means and where it comes from?

  • Failed to establish secure connection
  • [Step 0] Socket Error # 11002
  • [Step 1] Socket Error # 11002
  • [Step 2] Socket Error # 11002
  • [Step 3] Socket Error # 11002
  • [Step 4] Socket Error # 11002
  • [Step 5] Socket Error # 11002
  • [Unsecure] IOHandler value is not valid

11002 iohandler prtg

Created on Sep 2, 2021 9:02:27 AM

1 Reply



Hi there,

Basically, this means that the PRTG sensor was not able to establish a secure TLS connection to the page at the moment when the error message is getting displayed.

PRTG already does an automatic negotiation of the protocols which are used; starting with the most secure one.

What happens if you open the website in a browser at this time, is it reachable from there?

What exact version number of PRTG are you using, and which exact sensor type are you using?

Kind regards,
Felix Saure, Tech Support Team

Created on Sep 6, 2021 7:38:03 AM by  Felix Saure [Paessler Support]

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