I Have OS Catalina.DYMO Label printer software will not finish opening

Unfortunately the MacOS 8.7.3 on the DYMO website is really version 8.7.0 under the hood and does not use the latest DYMO API. It is however completely 64-bit! I combined the DYMO Label software 8.7.2 and replaced the 32-bit parts with the 64-bit versions from the 8.7.3 which results in a 8.7.2 version that is completely 64-bit! You can download it here: https://bit.ly/DLS8Setup

Have you tried to circumvent Apple's download security measures for downloading from an unapproved developer? In Security and Privacy system preference, at your own risk, try opening DYMO software with Allow downloaded apps from anywhere checked and see if it will open.

Just an install thread of what worked for me:

The 3rd option on my Security & Privacy page (Anywhere) doesn't exist on Catalina...

I added the Dymo 400 as a printer with default software first.

Then I tried two drivers (8.0, 8.7.2-64bit) from Dymo. They start install but fail with a message that it's not compatible with this version of my OS.

So I downloaded RichieBBB's driver patch (below) but get a fail to open because it's from an unidentified developer. I'm feeling dizzy from going in circles... But using "control" and "mouse click" then "open" on the unpacked RichieBBB DYMO Label v.8.pkg icon allowed it to run. Many requests to access locations (presumably for the Office add-ins). Then a warning about Sanford LP wanting to access/change extensions, which I ignored.

Local printer (Dymo and another) disappeared from Printers and Scanners, so had to reinstall. Opened Dymo Labelwriter software that now installed. Works! Then reinstalled other local printers...

all seems to work now.

Thank you.

You can contact DYMO support and ask them if they are providing 64-bit drivers for their label makers.

Ref: https://www.dymo.com/en-US/online-support/online-support-faqs

Did you follow the instructions from the installer i.e. "turn on label maker" and add to Printer preferences. The software is dated Feb.2, 2019 so it could very well be 64 bit, but to be sure follow Tesserax's advice and contact developer.

This is because MacOS Catalina has dropped support for 32-bit applications like DYMO Label printer, and it seems that Dymo has not bothered to update the application within the decade of warning time that Apple has given them.

If anyone has any solutions please do reply here!

I was using Turbo 450. Software was working ok with Catalina. Purchased Twin Turbo via Amazon. Must have been a return because there was no start up guide or install CD. Just tried connecting, but not available in printer list. Tried downloading software from DYMO, but Apple would not open because it couldn't be checked for "malicious content." Thought I might need to uninstall old software. BIG MISTAKE! Now what was working isn't. But! Now printer shows up in the printer list. Grrrrr... Now I need software and my addresses. I have emailed Dymo, but no response yet. I will try calling tomorrow. Restoring from backup doesn't work either. Can't figure out why the software was working, then all of sudden (quite sometime after upgrading to Catalina), I got the white circle with cross out over the app icon.

It worked!!! {{{HUGS}}} THANK YOU!

Great, sometimes you have to work outside the box.