Black line on the dock

I just restarted my Mac and the line disappeared.

The line is an indication that an update/ download is taking place, the folder above it is the destination, open the folder and you should find out what is being downloaded. Sometimes the progress bar remains after the download has completed, usually restarting is enough to get rid of it , or 'killing' the dock.

Try restarting the Dock.

Applications > Utilities > Terminal

Launch Terminal.

Wait until the $ sign appears .

Enter the command killall Dock

Press the Enter key on the keyboard. Wait until the prompt shows up.

Quit Terminal.

This does not work for me, still a black line under the Applications Folder...

Thanks! The thin black line disappeared after doing these steps for me, too.

Although the fix from Dominic23 worked, it doesn't solve the problem as to what that line is?

If I set my dock to the left hand side of the screen when the line appears, it remains at the bottom of the screen and is not attached to the docks positioning!?

Something of nothing really, just one of those things that grinds my gears and happens a lot 👿

Same thing here. The terminal trick killed it, only to have it reappear a few seconds later.

Could it have to do with Time Machine?

Or an update running in the background?

Seems to work. Thanks. Will watch to see if it returns.