I’m opening PDF files with search highlighting in embedded Acrobat by using the “search” open parameter in a URL.
Example:
http://example.org/doc.pdf#search="foo"
Sometimes this works (PDF opens with results highlighted) and sometimes it does not (PDF opens without results highlighted).
I figured out that the cause of the failure was the file extension being uppercase.
For example, the URL in the question would work but the following would fail:
The solution was to change the file extension to lowercase .pdf, but if anyone has a better solution, I will gladly accept a different answer.