Gmail - the image cannot be displayed because it contains errors

After sending an image file attachment with Gmail, the recipient said that they could not open the file.

Using Gmail's download link worked for me and I could open up the image.jpg file on my desktop.
However, an error message displayed when clicking on the "view" link.

Here is the error message:

I checked my original file and it opened on my mac without a problem.  Other forums suggested that the error was due to the color profile being in CMYK instead of the web standard sRBG. My image was in sRBG.

The error message was caused by the file extension being wrong.  I had accidentally added a JPG file extension. The file was actually a PSD.  I meant to save it out as a JPG, but clicked on an old file name and forgot to change the save format to JPG.

This online uploader service TrID identified the file type as being a PSD (photoshop document).