error message uploading/downloading iphoto

I'm trying to download photos onto my desktop from iPhoto and to upload them into Dropbox and I keep getting an error message that doesn't explain anything. What's happening?

Welcome to the forum. The error message may not explain anything to you, but until we know what it says we can't begin to guess. Please read the link in my sig and provide us more information.

Thanks, Jake.
So let me try again:
I am working on a Mac OS X Yosemite 10.10.3.
The software involved in Photos Version 1.0 (209.52.0).

The error message is as follows:
Export Complete with Errors
0 (of 1) filed have been exported to:
Desktop

The export operation failed to create a file for the photo identified below:
Filename: (the photo I chose)
Errors: Could not load image

Is there any more information that would be helpful to answer this question?
I already did Safe Mode, but that didn't seem to do anything, as well as Repair Permissions on HD, which was also ineffective.

Much better! Now someone who uses Photos can probably help. From the error message it looks like Photos couldn't find the image to export. Can you see the image in Photos? (I don't use Photos or iPhoto, so I'm guessing here.) Also, your original post said iPhoto, but the error message is Photos, so I'm wondering where the image file really is.

The problem is in Photos (I'm just used to calling it iPhoto). And yes, I can see the photos in Photo.

OK, I yield the floor to a Photos expert to come in and help you. I'm sure one will come along soon...