QZ Tray Certificate

Receipt printing and tag printing run through QZ Tray. Until this certificate is installed, QZ Tray does not recognise QuickDC as a trusted source and every print job is either blocked or buried behind an “untrusted website” confirmation prompt.

⬇ Download override.crt

Issued to: QuickDC QZ Signing Root CA (Quick Dry Cleaning)
Valid until: 18 July 2036
SHA-256: 70:E4:6A:0C:EF:C6:96:A3:4E:79:03:D8:70:2B:F8:DD:11:78:27:06:40:96:9E:73:D6:EC:D9:19:A6:66:14:42

This file is a public certificate — it contains no private key and is safe to distribute to every till. It does not replace the QZ Tray installer; install QZ Tray first, then add this file.

1. What this certificate does

QZ Tray only accepts print requests that are signed by an authority it trusts. Out of the box that is QZ Industries’ own certificate, which knows nothing about QuickDC. Dropping override.crt into the QZ Tray program folder adds the QuickDC signing authority alongside it, so signed requests coming from the POS are accepted silently.

It is a per-machine change: every computer that prints receipts or garment tags needs the file, and it survives QZ Tray restarts but not a QZ Tray reinstall or upgrade — reapply it after either.

2. Install the certificate

Save the downloaded file as exactly override.crt — the name is matched literally, and browsers sometimes append .txt or (1). Then move it next to the QZ Tray program files:

OS	Destination
Windows	`C:\Program Files\QZ Tray\override.crt` Copying into Program Files needs an administrator prompt. On 32-bit installs the folder is "Program Files (x86)".
macOS	`/Applications/QZ Tray.app/Contents/Resources/override.crt` Right-click QZ Tray.app → Show Package Contents to reach Resources, or use the terminal command below.
Linux	`/opt/qz-tray/override.crt` Needs sudo. This is the default path for the .deb and .rpm packages.

On macOS and Linux the copy is quicker from a terminal:

# macOS
sudo cp ~/Downloads/override.crt "/Applications/QZ Tray.app/Contents/Resources/override.crt"

# Linux
sudo cp ~/Downloads/override.crt /opt/qz-tray/override.crt

3. Restart QZ Tray

QZ Tray reads the certificate once, at startup — the file has no effect until it is restarted. Quit it properly rather than just closing a window:

Windows — right-click the QZ Tray icon in the system tray (bottom-right, possibly under the “show hidden icons” arrow) → Exit, then launch QZ Tray again from the Start menu.
macOS — click the QZ Tray icon in the menu bar → Exit, then reopen it from Applications.
Linux — pkill -f qz-tray && qz-tray &, or restart it from your desktop environment’s tray.

4. Verify it worked

Reload the POS in the browser so it reconnects to QZ Tray.
Open any order and print a receipt or a garment tag.
The job should go straight to the printer with no “an untrusted website is requesting access to your printers” dialog. That silent print is the confirmation — if the dialog still appears, the certificate is not being read.

You can also confirm the file you saved is the right one. It should print the fingerprint shown in the download card above:

openssl x509 -in override.crt -noout -fingerprint -sha256

5. Troubleshooting

Symptom	Cause / fix
The “untrusted website” prompt still appears	QZ Tray was not restarted, or the file did not land in the program folder. Confirm the path in the table above and check the name is exactly override.crt — not override.crt.txt. Windows hides known extensions by default; turn on File name extensions in Explorer’s View menu to see the real name.
Access denied when copying the file	The QZ Tray folder is protected. On Windows copy it via an Explorer window opened as administrator (or accept the UAC prompt); on macOS/Linux use the sudo commands above.
Printing worked before and stopped after an update	A QZ Tray reinstall or upgrade replaces the program folder and removes override.crt. Download it again and repeat the install.
POS says QZ Tray is not connected	This is a separate problem from the certificate — QZ Tray is not running at all. Start it, wait for the tray icon, then reload the POS. The certificate only affects trust, not the connection.
Certificate has expired	This certificate is valid until 18 July 2036. After that a replacement has to be issued and redistributed — contact the QuickDC team rather than editing the file.

Setup guide · maintained by hand, not generated from a test run.