My Mac is stuck at "Syncing" after updating my OS.

Hey ryofurue, thanks for the heads up and added info! 

You should be able to copy and paste your screenshot when replying to me. Alternatively, you can click the camera-like icon and attach it that way.

Do you have any proxy, VPN, firewall, security software, or even ISP/router settings that could be restricting traffic to the following Dropbox domains? 

If you do, try temporarily disabling those, to see if that helps.

Megan wrote:

I’d also like you to right-click on your local Dropbox folder directly, select “Get info” and send me a screenshot of the next window you’ll see. 

I haven't been able to find out how to send you the image.

I initially formatted the above message of mine using some quoting, but this website complains

Content Not Published
Your post contains invalid HTML. Remove the following invalid tags before publishing: a, span (style)

So, I copied the text and pasted it and posted. That's why quotations don't have any indication of quoting.

1. I started the machine. Dropbox is launched. "Starting..." -> "Syncing..." --- Dropbox was stuck here. I waited for 10 minutes before going to the next step.
2. I then quitted Dropbox and launched it again (from /Applications/). "Starting..." -> "Syncing 11 files..." -> "Syncing..." --- Dropbox was stuck here. I waited for 10 minutes before going to the next step.
3. I then quitted Dropbox, restarted the machine, and logged in when the machine got up. Dropbox was automatically launched. "Starting..." -> "Syncing 11 files..." -> "Syncing 19 files..." -> "Syncing...". I waited for 10 minutes. Nothing changed.

In the above, my reports about "Syncing XX files" may not be accurate. It's possible that I just missed those temporary messages.

During the above experiment, I was working on another Mac.  When I altered some files on it, they are synced on the problematic machine. So, the basic mechanism of syncing seems to be working.

Could you confirm where your Dropbox folder is currently located on your machine?

`~/Library/CloudStorage/Dropbox/` . . . I confirm that none of the directories is a symbolic link.

Feel free to also hover your mouse over the little Dropbox icon on your menu bar, next to your WiFi and clarify the version you're using, along with the app's current syncing status.

Dropbox 217.4.4417

Syncing...

I’d also like you to right-click on your local Dropbox folder directly, select “Get info” and send me a screenshot of the next window you’ll see.

I don't know how to paste the screenshot here. I'll try to send it you if I find a way to do so.

Hi ryofurue, thanks for bringing this to our attention.

Does the issue go away after rebooting your device or quitting and relaunching the app by any chance?

Could you confirm where your Dropbox folder is currently located on your machine?

Feel free to also hover your mouse over the little Dropbox icon on your menu bar, next to your WiFi and clarify the version you're using, along with the app's current syncing status.

I’d also like you to right-click on your local Dropbox folder directly, select “Get info” and send me a screenshot of the next window you’ll see. 

Keep me posted!