macOS Gatekeeper blocks the app

You see

You double-click Beam Bench.app for the first time. macOS refuses to open it, showing a dialog like:

"Beam Bench" can't be opened because Apple cannot check it for malicious software.

Or, in newer macOS:

"Beam Bench" was not opened because Apple could not verify it is free of malware.

macOS's Gatekeeper requires downloaded apps to be signed and notarized before they open normally. Current public Beam Bench builds are Developer ID signed and notarized, so this warning should be unusual.

First, download a fresh copy from beambench.com. If the fresh copy is still blocked, use one of the one-time approval options below.

Fix

One-time approval (recommended)

In Finder, navigate to your Applications folder.
Right-click (or Control-click) Beam Bench.app.
Choose Open.
The same warning appears, but now with an Open button. Click Open.
macOS remembers this choice. Future launches work normally.

Via System Settings

If the right-click trick does not work (newer macOS sometimes hides it):

Try to open the app normally. The block dialog appears.
Open System Settings → Privacy & Security.
Scroll to the bottom, there should be a message about Beam Bench being blocked.
Click Open Anyway.
Confirm.

Via Terminal (last resort)

If neither GUI method works:

sudo xattr -r -d com.apple.quarantine "/Applications/Beam Bench.app"

Removes the quarantine attribute that triggers Gatekeeper. Run this once, then launch normally.

Verify it worked

Beam Bench opens.
Subsequent launches do not prompt.

Still stuck?

Install Beam Bench.
Post in the Facebook group with the macOS version.