Could not establish trust relationship for the SSL/TLS secure channel about iis.webmanager HOT 4 CLOSED

For me, this error was caused by expiration of the self-signed certificates installed by the IIS.Administration component. Uninstalling and reinstalling this component created fresh certificates that are good for another two years. However, it looks like IIS.Administration is end-of-life. Does that mean this project is dead by extension?

from iis.webmanager.

I have the same problem.
I have uninstalled and reinstalled "IIS Management Scripts and Tools" from the server roles, restarted, but nothing helped.
My localhost certificate is expired, and thus the certificate of https://server:55539/ .
I have also tried removing the certificate and that has completely broken the IIS Management API.
Any ideas are welcome.
How can I set the certificate manually to a specific certificate in the WebHosting store?

from iis.webmanager.

The "IIS Management Scripts and Tools" server role does not help. That is not the IIS Management tool used in WAC.

Can you access https://server:55539/ directly? If it works, the certificate is fine. If not,

• Reinstall IIS Administration application on the server from https://github.com/microsoft/IIS.Administration/releases/tag/v6.0.0. That should update the certificate,
• If re-installing IIS Admin does not help, you might not have enough permissions to access it from the WAC. You need to give yourself permission by doing https://github.com/microsoft/IIS.Administration#:~:text=If%20you%20still%20don%27t%20have%20permissions

from iis.webmanager.

Originally, I could access https://server:55539/ , but I was getting a certificate error and I had to bypass this on the browser (which is expected). The expiration date on the certificate was on a past date.
But the IIS extension in WAC did not work at all, and I was getting the mentioned error.
Later, I removed a "localhost" certificate from the server the above API stopped working all together.

Thanks for your help.
I have managed to fix the problem now.
I have uninstalled "IIS Administration" from the "Installed Apps" addon/section in WAC (Windows Admin Center).
Uninstalling using the linked installer and an /uninstall flag did not work for some reason and it was leaving things behind that prevented a successful reinstall.
After that, installing fixed everything! :)

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