Exchange 2016 On-Prem Organization Add-in Error

Bigwil4555 101 Reputation points

I'm trying to add an Add-in to my Organization but I get an error message as soon as I click on Add-ins. I have the needed permissions to do this however I get:
Error: The request failed. The underlying connection was closed: An unexpected error occurred on a send.

I looked this up in Technet and Google but I found no answers. Any assistance is appreciated.

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Accepted answer
  1. Bigwil4555 101 Reputation points

    All right guys It was TLS 1.2. Though it was installed using IISCrypto the proper registry keys were not created. I located the proper registry keys from and create the proper reg file. I also had to create a registry change to .Net framework. Now my Add-ins screen looks like Lou's picture plus the add-in was originally trying to install. Thanks for the direction.

4 additional answers

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  1. Bigwil4555 101 Reputation points

    Lou, yes Exchange comes up as you have shown and there are no apps listed.
    I attempted to run the install using this EMS command: New-App -OrganizationApp -FileData (Byte[]) and I received the same error message at the command line with a lot more stuff.
    I really thought that would work.
    I'll try resetting IIS later tonight as it's my understanding on Server 2019 resetting IIS causes a reboot now.

    1 person found this answer helpful.

  2. Andy David - MVP 143.6K Reputation points MVP

  3. Xzsssss 8,861 Reputation points Microsoft Vendor

    Hi @Bigwil4555 ,

    See if this document helps:

    Check TLS 1.2 status with this cmdlet: Invoke-WebRequest

    Best regards,

    If the response is helpful, please click "Accept Answer" and upvote it.
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  4. Bigwil4555 101 Reputation points

    Lou\AndyDavid, I too believe this is related to my TLS settings. Even though I have TLS 1.2 enabled the registry keys aren't matching what Microsoft says they should. I'll be making the change tomorrow night and will keep you posted.
    Appreciate the assist,

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