Issue

AP Essentials Connect records the following error when attempting to connect to AP Essentials:

• Unable to call AP Essentials Logging Service ReadSoft.Services.Client.ClientException: The underlying connection was closed: An unexpected error occurred on a send.
   

Cause

The "Unable to call AP Essentials Logging Service" error can appear for several reasons.

However, the most likely cause of "The underlying connection was closed: An unexpected error occurred on a send" is that the current installation and/or configuration of AP Essentials Connect is not allowing a TLS 1.2 connection to be negotiated. 

**Note:  TLS 1.0 & 1.1 have been depreciated and are no longer allowed as of Monday July 10, 2023.

Solution

Upgrade AP Essentials Connect to a version that supports TLS 1.2.

**Please note:  only versions 10.4.7451 and above, in conjunction with Microsoft .Net 4.8, are TLS 1.2 compatible.

Microsoft .Net 4.8 must also be installed first, before installing the latest version of AP Essentials Connect.

Please refer to the Knowledge Base Articles listed below for additional information on upgrading AP Essentials Connect.

If connections still fail after the upgrade, there could be settings within the O/S that are either not allowing the TLS 1.2 protocol, or preventing stronger cryptographic algorithms which provide support for TLS 1.2 from being negotiated by .Net applications.  Please refer to this Knowledge Base article and the Knowledge Base Articles listed below for additional information on these settings.
 

Level of Complexity 

Moderate

Applies to  

References

AP Essentials Connect version info
 

Upgrading AP Essentials Connect to support TLS 1.2

Login Failed error during configuration of AP Essentials Connect

AP Essentials Connect System requirements