Cannot edit pages due to a web.config redirect link

Issue

A customer discovered that some pages could not be edited using the editing pencil. They can only be edited by going first to the Pages tab and choosing the Edit option from there. All the user roles are experiencing the same behavior.

Product: DNN Evoq 9.1

Diagnostic

In the content of the pages, there is a section with a reference for files, like below:

<a href="/Document-Repository?Command=Core_Download&amp;EntryId=3483" target="_blank">
<img src="https://server.domain.com/resources/HR/policies/_layouts/images/pdfimage.png">Specific-File.pdf</a>

The problem is a redirect rule in the web.config file, that sends requests from the web server server.domain.com to another web server, named echo.domain.com. As a side effect, the image file pdfimage.png is not found, then the User Interface doesn't activate the Edit icon,as a security measure.

Resolution

The fix identified for this issue was to move the file to the redirection target server (in this case, echo.domain.com), so the image could be found when the User Interface works in the background to load all references, and then the Edit option became available to be clicked.