How to add date value in an error message?

Summary:

Hello everyone,

we are trying to add a date value in an error message. We used a Object Validation Rule type, I found out that it is possible with Get date in custom format.

But we are having this kind of error:

Can you give us an example on how to implement date values in an error message. ?

Thank you in advance.

Content (required):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):