Hello, my user reported an error message “Form Not submitted” and I added ?debug=1 to the end of the web form URL and received the below error message, anyone know what this message means and how to fix it?

Hello, my user reported an error message “Form Not submitted” and I added ?debug=1 to the end of the web form URL and received the below error message, anyone know what this message means and how to fix it?
Hello,
In the black box on the bottom left side there is a message for “Slug” with a non-valido format. Is “Slug” a field in the web form?
Does that webform worked before or never run it successfully?
Best,
Alexandre
hello,
it worked but still don’t know why I received this error message.
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