signature field should not have other characters except A-Z, a-z and _ while prepare a form in Adobe DC

Hi social_skillebe4,

Thank you for reaching out and sharing the information.

It looks like you are using an Acrobat Sign form, and this behavior is by design.

If you are simply trying to create a PDF form with a signature field, please follow the steps below:

• Click on the three dots next to the “Prepare a form” title in the tool pane on the left.

• Select "Remove signing options."

• Now, try to add the signature field again and see if that works.

For more information on creating a PDF form, refer to the following help document: Convert documents to PDF forms.

Let us know if this helps!

Thanks,

Meenakshi