Last night I read through a bunch of help messages on “Unable to create directory…” and “The uploaded file could not be moved” — after I created the uploads directory myself. I checked directory permissions and tried assorted things with no luck.
This morning, for kicks, I added a “/” in front of the default “wp-content/uploads” creating “/wp-content/uploads” and was able to upload. I have no idea what type of server my site is on, etc. I just know that this worked and thought I’d pass it on.