I added the necessary directories for tracing, but unfortunately I don't see anything that gives me additional clues to this issue. Please let me know how I ought to proceed.

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I found the issue (that was difficult to debug with ssl turned on):

HTTP Error 500.19 - Internal Server Error

The requested page cannot be accessed because the related configuration data for the page is invalid.

Config Error: This configuration section cannot be used at this path.
              This happens when the section is locked at a parent level.
              Locking is either by default (overrideModeDefault="Deny"), or set explicitly
              by a location tag with overrideMode="Deny" or the legacy allowOverride="false". 

Config Source   34:       <security>
                35:         <access sslFlags="SslNegotiateCert" />
                36:       </security>

from identityserver2.

Huzzah! Problem solved! You've got to set SSL Settings to Read/Write in IIS.
IIS>Server>Feature Delegation>SSL Settings>Read/Write

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