SSL connection error when hosting on IIS with https

Question

The filemanager on my application (Blazor Server and .Net 5.0) reports an error only when the application is hosted on Microsoft IIS.

The error is "The SSL connection could not be established, see inner exception" and occurs even before loading the data.
The error only occurs if I try to use the https protocol. If I try to access the application using http it works fine.

The issue only occurs on IIS. When trying to do the same using Visual Studio and IIS Express, the filemanager works for both http and https usage.

I've installed a self certificate on my machine and i'm also using that in the ssl settings of IIS for the website. The browser trusts the certificate.

I've tried to use the onError event of the filemanager to gather additional info, but I can't access the inner exception to try to understand what is causing this issue, therefore I can't resolve it.

I've reproduced this issue using a sample application with the latest syncfusion version. Please find it attached.
When publishing, I choose the folder method.
Thank you for your support.

Attachment: FileManagerSslTest_7ac04f81.zip

Indhumathy Loganathan · Answer

Hi Luca, 
 
Thanks for contacting Syncfusion support. 
 
We have validated your reported query in File Manager component. The SSL connection issue usually occurs due to browser’s security policy. HTTPS requests without SSL certificate will get rejected and cause the reported error.   
  
We suggest you to use the HTTP URL instead of HTTPS and remove the app.UseHttpsRedirection() (which force convert HTTP URLs into HTTPS) in Startup.cs file.   
 
Please check whether the provided details help you. If not, get back to us with details for further assistance.  
  
Regards,  
Indhumathy L

Luca · Answer

Hi, The normal HTTP url already works without removing the

app.UseHttpsRedirection()​ line.As for the certificates, we do use a self signed one which is correctly installed, as the browser does signal the website to be safe (the red line over the https in the url bar is not dislayed), even if it's a self certificate.For security purposes, our application should run on https, so this is not a suitable solution for us.In addition, everything else on the website works, including our custom httpclient in the blazor frontend which communicates to the asp net core server, the only thing that is not working is just the filemanager.I suppose you're using something like a httpclient on the code for the filemanager library. Could you please check the exception that it throws in that use case, before the error is wrapped to be inserted in a FileManager.FailureEventArgs object? Thank you

Indhumathy Loganathan · Answer

Hi Luca, 
 
We suspect that this may be a general issue on IIS. Currently we are checking this internally at our end. We will provide further details on 6th September, 2021. 
 
We appreciate your patience. 
 
Regards, 
Indhumathy L

Indhumathy Loganathan · Answer

Hi Luca, 
 
We have validated your reported query “SSL connection error”. Since the reported issue occurs due to general IIS certificate issues, we suggest you to try out the suggestions from the below blogs. 
 
https://stackoverflow.com/questions/30240014/enabling-ssl-on-localhost-iis 
 
https://stackoverflow.com/questions/39183773/enable-ssl-in-visual-studio 
 
https://www.host.ie/blog/what-does-ssl-connection-error-mean-and-how-to-fix-it/ 
 
Kindly try the above ways and get back to us if you face any difficulties. 
 
Regards, 
Indhumathy L