Browse > Collections > New Collection
Fill in required information
For "Type of challenge, if any," choose prompt meme
Check "Sign-up open?" if not already checked
Allow Descriptions, 1 Fandom, 1 Character, 1 Relationship, 1 Additional Tag
Follow the "Prompt Form" link
Fill in one of the tag fields with a canonical tag
Follow the "Add Prompt" link
Fill in one of the tag fields with a noncanonical tag
Enter text in the Description
I am redirected to the sign-up edit page (https://test.archiveofourown.org/collections/NAME/signups/###/edit) with the error "That prompt would make your overall sign-up invalid, sorry."
The information I entered is nowhere to be seen.
The new prompt form should be reloaded and all of my information should still be filled in. (Redirecting me to the sign-up edit page would also be acceptable if my information were saved.)
There should be an error like the one you get if you attempt to use a noncanonical tag while first submitting or editing the sign-up (refer to screenshot for what the error for sign-ups looks like):
Sorry! We couldn't save this request because:
These tag type tags in your request are not canonical and cannot be used in this challenge: tag name. To fix this, please ask your challenge moderator to set up a tag set for the challenge. New tags can be added to the tag set manually by the moderator or through open nominations.
If you try using a noncanonical tag while using the Edit Sign-up page, you get the desired error message. This is true whether you're editing the current request or adding a new one.