Preventing the duplication of a custom field value

[Osama Al-Areky]

Hello,

I want to prevent the user from entering a duplicated value to a custom number field so that it prevents the creation of the issue or at least it gives an error message or adds a duplicated label or mark or something. Is there a way to do that please?

Thank you,

[Joe Pitt]

Nothing out of box would do that. You may be able to write a script, but you would need to scan the entire list of values for the field until you found a match to either allow or reject the entry.