Sometimes there is a mismatch in dates between Canvas and Turnitin Feedback Studio (LTI 1.3) Classic assignments. The error message below is the identifying symptom of the problem.

Turnitin Error

Sorry, we could not process your request.
Turnitin assignment could not be created.
date_post — Post date must be after the start date 

Fix the conflict

1. Edit the assignment settings in Canvas, temporarily removing the Available From (Start on the Tii side) date. Save the change.
2. Open the Turnitin Assignment from Canvas. 
3. Select Settings. 
4. Change the Feedback Release Date so that it is at least one minute after the desired Available From/Start date. 
5. Save the changes. 
6. Edit the assignment settings in Canvas, restoring the desired Available From/Start date.
7. Save the changes. 

An alternate assignment copy option is available for Standard (not Classic) assignments that makes it easier to copy assignments between classes while avoiding date conflicts. 

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