Thursday 21 January 2016

DYMO Label v.8: Fatal Error - Cannot create instance of 'MainWindow' defined in assembly

Error on launch of DYMO Label v.8:

Cannot create instance of 'MainWindow' defined in assembly 'DYMO.DLS', Version=, Culture=neutral, PublicKeyToken=5426002a38745af9'. Exception has been thrown by the target of an invocation. Error in markup file 'DYMO.DLS;component/MainWindow.xaml'.

This issue can be commonly be caused if the DYMO printer is shared from a print server (eg: \\server\printer) and is no longer available or the share name has been changed.

To resolve:

Review the printer object in Devices and Printers.
Delete the printer object and reinstall via the print server.


Download and run Microsoft.NET Framework Repair Tool:

Uninstall DYMO Label v.8 from Programs and Features
Delete printer object from Devices and Printers
Remove driver (Devices and Printers > select a printer > Print server properties > Drivers)
Delete C:\ProgramData\DYMO
Delete C:\Users\username\AppData\Local\DYMO
Delete C:\Users\username\AppData\Local\Sanford,_L.P
Delete C:\Users\username\Documents\DYMO Label (optional)

Open Registry Editor
Browse to HKEY_CURRENT_USER\Software\ and delete DYMO key
Browse to HKEY_LOCAL_MACHINE\SOFTWARE\ and delete DYMO key

Restart the computer
Download and install latest version of DYMO Label:
Install printer locally or from print server


  1. Mine did this as well, followed your steps, and then after re-installation from a clean start the problem reoccurred at first run of the DYMO Lable v.8 software. Interestingly, I could get the software to start up successfully if I, "Run As Administrator", which is interesting.

  2. My Problem was that the password for the computer sharing the printer was not added correctly

  3. For me it was as simple as deleting the printer and reinstalling it. In so doing I discovered that there were 2, so I deleted both. It might have had something to do with the root cause of the problem.