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How to resolve the Microsoft Dynamics GP error message: "Invalid number of parameters"?


You have just installed AvaTax or have updated your AvaTax connector. When you pull up GP, you see the error below:

"Invalid number of parameters. \r"


Microsoft Dynamics GP


  • This error message indicates the AvaTax .dll hasn't been properly registered on the machine in question.
    • Make sure you're a local administrator to the machine in question; without proper permission, the .dll can't be registered
    • In c:\program files\avalara\avatax connect adapter\ right click and createa text document and copy and paste the following text:
      • C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\regasm.exe avalara.avatax.adapter.dll /unregister
        C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\regasm.exe avalara.avatax.adapter.dll /tlb /codebase
  • Name the file register.bat and place it in the Binfolder of your Avalara directory on the local drive.
    • The default location for this folder is c:\program files\avalara\avatax connect adapter\
  • Once the file is created, run the file and test connection again.
  • If this still hasn't resolved the issue and you're in a 64 bit environment, try the following:
    • Go to Start > Accessories and then right-click the Command icon and select Run as administrator
    • Once in the command prompt, navigate to the Bin folder where the batch file above was created
    • Type register
  • You may also try uninstalling the AvaTax Configuration and reinstalling it to resolve this issue
    • The AvaTax DLLs are usually registered during the install process