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Information in this article applies to:

  • C166 Version 4.05
  • C51 Version 6.01


When I try to download the latest software from the web for the C166 Version 4 or the C51 Version 6, I receive the following error message:

That is an invalid serial number.
The serial number must be in the form xxxxx-xxxxx-xxxxx.

I entered the correct serial number and I still get this error message. What could be wrong? My serial number is not in this xxxxx-xxxxx-xxxxx format. Could that be it?


Serial numbers for C166 Version 4 and C51 Version 6 are formatted differently than previous versions.

  • To download the C166 Version 4 update, you must already be a licensed user of C166 Version 4.
  • To download the C51 Version 6 update, you must already be a licensed user of C51 Version 6.

You cannot use the C166 Version 4 update to upgrade your C166 Version 3 tools. Likewise, you cannot use the C51 Version 6 update to upgrade your C51 Version 5 tools.


You must have licensed C166 Version 4 or C51 Version 6 to download the latest updates. To do so, contact our sales department. When you upgrade to the latest tools, you will receive a new serial number that is in the correct format. Then, you may download these new updates from the web.

Last Reviewed: Tuesday, July 19, 2005

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