Printing DYMO labels with the Cratebase Chrome extension

Label printing troubleshooting (DYMO)

Cratebase prints labels through the DYMO Web Service — a small program that DYMO installs on your computer and that runs quietly in the background. When you click “Print label,” Cratebase talks to that service over a secure local connection: https://127.0.0.1:41951 for 450-family printers, or https://127.0.0.1:62170 for 550-family printers running DYMO Connect (Cratebase checks both automatically). Almost every printing problem comes down to that service either not running or not being trusted by your browser.

This guide walks you from a clean install through the most common issues. Start at Step 1, then follow the decision tree.

Step 1 — Install the correct DYMO software

Download the latest software directly from DYMO:

Choose DYMO Connect for Desktop (DCD) for your operating system (Windows or Mac). A few important rules:

  • Pick ONE program, not both. Install either DYMO Connect for Desktop or the older DYMO Label Software — never both at the same time. Having both installed is a common cause of broken printing.
  • DYMO LabelWriter 550 / 550 Turbo / 5XL require DYMO Connect for Desktop. The older DYMO Label Software will not work with these printers.
  • Install your web browser first, then install DYMO. The DYMO Web Service registers itself with the browsers present at install time. If you install or switch browsers afterwards, reinstall DYMO.
  • On a Mac, reboot after installing. This is frequently the difference between the Web Service starting correctly and not starting at all.

After installing, plug in your printer, open DYMO Connect for Desktop, and print a test label from within the DYMO app itself. If that fails, the problem is with DYMO or your printer, not with Cratebase — fix that first.

Step 2 — The decision tree

Work through this in order. Most people are fixed by the first two branches.

If Cratebase shows “DYMO Web Service not found. Please ensure DYMO Label Software or DYMO Connect is running.”, that one message can be caused by either a certificate problem (Issue A) or the service not running (Issue B) — the test URL below tells them apart.

Can you print a test label from inside the DYMO app itself?
│
├─ NO  → The DYMO software or printer is the problem,
│        not Cratebase.
│        • Is the printer powered on and connected?
│        • Reinstall the DYMO software, then REBOOT
│          (see Step 1).
│        • Still failing? Contact DYMO support.
│
└─ YES → DYMO itself works. Now the issue is the browser
         talking to the DYMO Web Service. Open the test URL
         (Issue B, step 4) in your browser. What do you see?
         │
         ├─ Certificate warning ("connection is not private",
         │  an SSL/certificate error)
         │     → The secure certificate is the problem.
         │       Go to ISSUE A.
         │
         ├─ "Can't connect" / nothing loads /
         │  connection refused
         │     → The Web Service isn't running.
         │       Go to ISSUE B.
         │
         ├─ A short text response (the service is alive),
         │  but Cratebase still can't print
         │     → The browser is blocking the connection.
         │       Go to ISSUE C.
         │
         └─ Worked before, suddenly stopped
               → Most likely an expired certificate.
                 Go to ISSUE A, then, if needed, the
                 clean reinstall in ISSUE E.

Issue A — SSL / certificate errors

This is the most common cause. An error such as net_http_ssl_connection_failed (or a browser warning when opening the test URL) means your browser reached the DYMO Web Service but couldn’t establish a trusted secure connection. The certificate that DYMO installed is either untrusted, missing, or expired.

Fix order:

  1. Check whether the certificate has expired. Expired DYMO certificates are a frequent cause and cannot be “trusted” back to life — they must be regenerated (see step 4 below, or Issue E).
  2. Trust the certificate (see the platform notes below).
  3. Fully quit and reopen your browser after any certificate change. Browsers cache the old result for the session and won’t notice the fix until restarted.
  4. If the certificate is expired or missing, reinstall DYMO to generate a fresh one (Issue E).

On a Mac

The certificate lives in Keychain Access.

  • Open Keychain Access via Spotlight: press ⌘ + Space, type “Keychain Access,” press Enter. (On recent macOS versions such as Sequoia, Keychain Access is no longer found under Finder → Go → Utilities, so Spotlight is the reliable way to open it.)
  • Search for DYMO or DLS.
  • Double-click the certificate, expand the Trust section, and set the top option (“When using this certificate”) to Always Trust.
  • Close the window — you’ll be asked for your Mac password to save the change.
  • Quit and reopen your browser.

On Windows

  • Reinstalling DYMO Connect for Desktop normally re-registers a valid certificate automatically.
  • If problems persist, run the clean reinstall in Issue E.

Issue B — The DYMO Web Service isn’t running

If clicking print does nothing, or you see “service not reachable” / “connection refused,” the background service is likely stopped or was blocked from starting.

  1. Make sure DYMO Connect for Desktop is installed and has been opened at least once. Opening the app starts the Web Service.
  2. On a Mac, reboot if you haven’t since installing — the service often doesn’t start until the first restart after install.
  3. Check your Mac’s security settings (Mac only). macOS sometimes blocks the DYMO helper from running:
    • Apple menu → System Settings → Privacy & Security.
    • Scroll to the Security section near the bottom.
    • If you see a message that DYMO software “was blocked,” click Allow Anyway / Open Anyway, then relaunch DYMO Connect.
    • This approval button only appears for a short time after the block — if you don’t see it, reopen DYMO Connect to trigger it again.
  4. Test the service directly. In your browser, visit https://127.0.0.1:41951/DYMO/DLS/Printing/StatusConnected — this is the exact address Cratebase checks. (For a 550-family printer running DYMO Connect, use https://127.0.0.1:62170/DYMO/DLS/Printing/StatusConnected instead.) A short text response such as true means the service is alive. A “can’t connect” error means it isn’t running; a certificate warning means it’s running but untrusted (go to Issue A).

Issue C — The browser is blocking the local connection

If you get a “Your connection is not private” warning or the print silently fails in one browser but works in another:

  1. Confirm the certificate is trusted (Issue A) and restart the browser.
  2. Try the test URL from Issue B, step 4, directly. If you can reach it and accept it there, return to Cratebase and retry.
  3. Make sure DYMO was installed after the browser (Step 1). If you recently changed or updated browsers, reinstall DYMO.
  4. As a quick check, try a second browser. If printing works there, the issue is isolated to the first browser’s certificate trust — repeat Issue A for it.

Issue D — Something else is using the port

Rarely, another program occupies the port DYMO needs (41951) and the secure connection fails in confusing ways.

  • Mac: open Terminal and run lsof -nP -i :41951. If anything other than a DYMO process is listed, that program is the conflict — close it and restart the DYMO service (or reboot).
  • Windows: restart the computer to clear most port conflicts; if it recurs, contact support.

Issue E — Clean reinstall (the reliable reset)

When the certificate is expired or corrupted, a plain reinstall sometimes reuses the broken certificate. A clean reinstall fixes this:

  1. Quit DYMO Connect for Desktop completely.
  2. Uninstall DYMO Connect for Desktop.
  3. Mac only: open Keychain Access (Spotlight → “Keychain Access”), search DYMO / DLS, and delete the existing DYMO certificate so it can’t be reused.
  4. Reinstall the latest DYMO Connect for Desktop from the DYMO website.
  5. Reboot (especially on Mac).
  6. Open DYMO Connect, print a test label from the DYMO app, then retry in Cratebase.

Still stuck?

If you’ve completed a clean reinstall and a test label still won’t print from the DYMO app itself, the issue is with the DYMO software or hardware. Contact DYMO support with your operating system, browser, and printer model.

Still stuck? Get in touch — we're happy to help.