Camera Upload Error on Mac OS High Sierra/ Photos...Could Not Be Imported

I got a solution that worked for me from Dropbox Support. Thought I'd share it here for those who might benefit:

The application "Image Capture" which apparently comes with Macs -- who knew? -- can act as a "middleman" in the process to transfer images to Dropbox.

• Go to the Spotlight Search (top righthand side of your computer) and type "image capture".
  
  
• When it comes up, select your phone from the interface on the lefthand side of the app.
• The images from your phone will pop up in the main window of the app. Select those which have not been imported. 
• (You might want to click the box that says "delete after import" or "Keep originals" at the lower left of the app.) 

• Select Other -> Dropbox -> Camera Uplpads in the "Import To" dropdown.
• Click on the "Import" or "Import All" button and it will import.

Most of these steps don't have to be repeated on subsequent uses.

As I mentioned, I'm not thrilled with this "workaround," but I suppose it will do until Dropbox engineers get around to fixing what is obvious problems.

I might have a fix (or at least a better workaround than using the "Image Capture", since that doesn't use the same naming format as Dropbox and you might end up with duplicates once importing works again - at least I get file like "IMG_9365.JPG" instead of "yyyy-mm-dd hh:mm:ss.jpg").

On your iPhone, go to Settings > Photos.  At the very bottom, toggle "Transfer to Mac Or PC" from "Automatic" to "Keep Originals".  After doing this, I reconnected my iPhone and importing worked.

Note: This might transfer your current photos as HEIC files instead of JPEGs.  I'm not a big fan of this HEIC format, but eh, at least I have importing now.  If storing HEICs make you sad, I believe you can go to Settings > Camera > Formats and toggle it over to "Most Compatible", so future photos will be in JPEG.

My environment is as follows:

MacBook Pro, OS X 10.13.4

iPhone 8, iOS 11.3.1

Dropbox app on OS X: Stable Build 49.4.68

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1. Additional notes while debugging:
   I noticed that while importing fails when the setting is set to "Automatic", certain photos do get imported.  These consisted of iPhone screenshots and some low-res close-ups of stuff.
2. I found https://www.dropboxforum.com/t5/Syncing-and-uploads/Since-iOS-11-upgrade-camera-uploads-stopped-working/td-p/242509, which led me to suspect HEIC or image formats being the problem (again), especially in light of (1).
3. I was able to confirm that if I took a photo, switched the setting back to "Automatic", then reconnected my phone, the import process would fail with the error message.