https://forums.autodesk.com/t5/installation-licensing-forum/the-serial-number-you-entered-is-not-valid-try-again-1/m-p/5800630#M135609 Hello giovannibn and welcome to the Autodesk community! <BR /><BR />It looks like you're getting an "Invalid Serial Number” message or having trouble with your product key while trying to register and activate your Autodesk software. The following article(s) should help you resolve the problem: <BR /><BR /> Click <A href="http://knowledge.autodesk.com/support/autocad/troubleshooting/caas/sfdcarticles/sfdcarticles/Top-Five-Reasons-Why-You-May-Receive-a-Serial-Number-Error-During-Activation.html" target="_blank">Top reasons why you may get a Serial Number Error during Activation</A> <BR /><BR /> And check <A href="http://knowledge.autodesk.com/support/autocad/troubleshooting/caas/sfdcarticles/sfdcarticles/Error-Serial-number-invalid.html" target="_blank">Error: "Invalid serial number" (standalone activation)</A> <BR /><BR /> For product key information: <A href="http://knowledge.autodesk.com/customer-service/installation-activation-licensing/get-ready/find-serial-number-product-key" target="_blank">Finding Serial Numbers &amp; Product Keys</A> <BR /><BR /> If you’re having an issue with your product key, please make sure that you are using the correct one for your product (especially if your product comes from a suite). Finally, you should type then numbers and letters in. We do not recommend copy/paste. Wed, 02 Sep 2015 20:24:07 GMT Otto 2015-09-02T20:24:07Z