Have you tried the 'Windows' key?

I use a Mac and the 'Command' key.

I have tried almost all keys, but no luck. Windows key doesn't work either.
Multiple selction always works with my Mac. Now on Windows, I'm stunned, that this simple task is a problem.

Reading the release notes of 8.4.2:

"Fixed inability to ctrl-click or command-click file manager results to select them in bulk (thanks dimger)"

Seems that this actually hasn't been fixed?

How about 'ctrl' + 'space'?

This doesn't help either. Tried multiple selection now on a clean test installation, and it worked, then stragely didn't work anymore. Thought the issue was maybe be on my side, but i have no clue where to investigate.

So what keys r u using now?

As mentioned above, SHIFT + click works, but this way i can only select files next to each other.
No other key works for multiple selection, as i would expect from CTRL + click.

Updated to 8.4.3 now, but CTRL + click for multiple selection of files still doesn't work.

UPDATE:
Now i have tested this
- on several installations of concrete5 8.4.2 and 8.4.3
- on different servers
- with different themes (including elemental theme)
- on a clean installation of concrete5 8.4.2 without any add-ons or themes installed
- on Windows 10 and Windows 7 machines
- with different browsers: Firefox, Chrome, IE 11, Edge.

Result:
It's possible to select a bunch of files next to each other by SHIFT + click.
It's not possible to select multiple files in the file manager by CRTL + click.

The second option is very much needed if we have to select files in order to be able to add them to file sets easily.

I checked this on macOS now - no problem with selecting multiple files by CMD + click.

So this is a Windows-related issue which should be solved.

If you are still struggling I just managed to get it working on windows by pressing the Windows key + Ctrl key. nb. The Windows key MUST be pressed and held first before the Ctrl key.

Hope it helps.

Unfortunately I'm not able to reproduce this. Pressing the Windows key does not help.

Windows 10 64Bit
Firefox 67.0.1
concrete5 8.5.1

I reported this issue to the bug trakcer in october 2018, and it was confirmed.

https://www.concrete5.org/developers/bugs/8-4-3/8.4.2-and-8.4.3-cant...

It was also reported to GitHub by @mnakalay

https://github.com/concrete5/concrete5/issues/6919...

It will be fixed in 8.5.2 !