401 Error - HMAC-SH256 (D2L)

401 Error - HMAC-SH256 (D2L)


Error Code Cause

Users will see this error when they click a link to view a VitalSource eTextbook inside their LMS, but an Incorrect OAuth Signature method was used during the initial configuration.


Student / Faculty

  • Please reach out to your instructor and inform them of the error so they may reach out to the team that configured the link inside your institution's LMS. 

LMS Administrator

  • Update the LTI Tool in the LMS to use the OAuth Signature method: "HMAC-SHA1"
  • If you received notice of the error, test the link to see if the publisher enabled rights to the title.


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