Is this one particular file, or with .RAW files in general?
This is with a class of raw files that are generated by a particular type of scanner. I've tried more than one file, and the same file with both instances of Photoshop, and a file that opens on one system does not get to the Photoshop Raw Options dialog box on the other. The fact that I'm able to open the file on one system indicates that there isn't a problem with the file. Furthermore, on that system I can enter different options and it will open even if the result is garbage. The fact that the other system doesn't even get to the dialog box tells me there's something wrong with the configuration, and while I've looked through menus extensively, I have no idea what aspect of the configuration could cause this kind of issue. Could it be trying to run a script?
If I try just "Open", it says "Could not complete your request because it is not the right kind of document." I assume without a standard extension (in this case, it comes with an extension of "XYZ", but I've tried changing it to "RAW" and other things, with no change) or magic number at the beginning of the file, PS has no idea how to handle it. By using "Open As.." and selecting Photoshop Raw, I'm (normally) able to tell it how much header to skip, how many bytes per pixel, what endian to use, and the aspect ratio of the image. That's all necessary for a typical raw image. In other words, I need that dialog box.
Did you try resetting all Photoshop tools and your Photoshop Preferences on the failing machine?
Good suggestion, but I just tried and it didn't have any effect. I did "Reset Preferences on Quit" and both "Restore Defaults" and "Clear Tools" in Customize Toolbar. I should mention that is a fresh installation of PS CC 2017, and I had the same problem with PS CC 2015.
I discovered a workaround to this problem that probably provides a hint about the cause, but for now I have no idea what that is. I noticed that when I tried to open image files using "Open As..." specifying various file types, the error messages usually referred to a different file type. For instance, trying to open as a Photoshop RAW gave a JPEG error. Trying to open a JPEG as a JPEG yielded a Photoshop 3D error. I determined that whatever file format I selected, it was trying to use the format 5 items above that one in the menu. The ones relevant to Photoshop RAW show up like this:
PIXAR [Note that my other system has PLY after PIXAR]
Portable Bit Map
When I select Photoshop RAW, it gave a JPEG error. When I select Portable Bit Map, it opens the RAW file!!!! Therefore, there is apparently an offset of five items between what is selected and what it actually does. Weird. If someone has an idea why this is happening and how to fix it, I am all ears.
OK, I just realized that the system that is acting funny is missing exactly five file types in the Open As... menu, relative to my other system that is working. They are:
Google Earth 4
So I think the question is either why are they missing on the one system, and why doesn't the system know how many file formats it can open?