Today I ran across an issue where someone had created links within a classic document library that redirected users to documents stored in a different library. This is easy to do, but for some reason those links were now leading users to blank .aspx pages instead of the intended document.
Note that users weren’t taken to an “invalid” or “can’t be found” error page, but a completely blank page with a URL ending in .aspx. If you’re being redirected to anything other than a blank page the following solution probably won’t apply to you.
I figured out that, somehow, the library in question no longer had the “Link to a document” content type included. You normally can’t delete a content type that is in use, but with the right permissions and perhaps a migration tool or script, anything is possible. Without the content type on the library, the links that once worked under that content type now could not.
Important: The links are not necessarily broken – do not delete them. Once the content type is added again, they should work unless the original URLs have actually changed.
To re-add the link/shortcut content type to the library, follow these directions (same as if you were adding it for the first time):
1. Go to Library > Library Settings

2. Choose Advanced settings

3. Set Allow management of content types to Yes.

4. Click OK to save changes.

5. Under Content Types choose Add from existing site content types

6. Select Link to a Document and Add >.

7. Click OK.

Now check your links, and they should work!