Solutions

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

Modified on 2025-06-10 14:54:09 +0200

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

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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

Sep, 2021 - Permalink

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

Article CommentsAttention: This article is a record of a conversation with the Paessler support team. The information in this conversation is not updated to preserve the historical record. As a result, some of the information or recommendations in this conversation might be out of date.

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Attention: This article is a record of a conversation with the Paessler support team. The information in this conversation is not updated to preserve the historical record. As a result, some of the information or recommendations in this conversation might be out of date.