There are several reasons why this can happen:
- You have logged in with a 3rd Party Provider (e.g. Facebook) before that has the same email.
You will need to change the email of your third party account on Autodesk 123D. First login to 123D with your 3rd Party account. Then go to My Profile > Edit Profile > "autodesk account" > Edit Account. Make sure you are editing your Account Email, NOT the Profile Email.
- You changed your email on 123D to a conflicting email on Tinkercad.
Unfortunately this is not allowed, but we don't have a way for 123D to detect this conflict immediately. Please change your email on 123D to another and try again.
- None of the above.
- Please send us the email address you used to login with, and provide us all the steps you took to get this error, along with any applicable screenshots. Thank you!