This is to help other people who may be having this issue.
I was using D365 Portals but when accessing the Web Page, I received this error.
Script Error
TypeError: Cannot read property 'webpage' of undefined
at eval (eval at RunHandlerInternal (URL of CRM), <anonymous>:1:19)
at RunHandlerInternal
at RunHandlers
at OnScriptTagLoaded
or 'Cannot read property of WebForms' or 'adx is not defined at eval'
I was unable to access certain information like Additional Settings and creating Entity Form Metadata would error out as well.
Mousing over some of the forms information, you can see that it says 'Request to the server has been blocked by an extension'
Looking through the source (and just noticing that the form looks different to the CRM's look and feel), you can see that some parts of the form are iframes linking to external URLs.
The CRM form depends on the iframes. So, all you have to do is disable your adblocker or any content filtering you have.
Regards,
Jarren Ong
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