This validation is automatically used for file fields (see Unauthorized extensions).


<UnauthorizedExtensions rename="false" extensions="aspx,jpg" />       
     <Extensions name="All" deny="aspx,cs,exe" />
     <Extensions name="Images" allow="jpg,png,gif,tif,jpeg,tiff,bmp" />
     <Extensions name="PDF" allow="pdf" />

The UnauthorizedExtensions node is global to all file fields.

The AuthorizedExtensions node is specific to a file field (configuration in the field parameters).

If an Extensions node contains both "deny" and "allow", any extension in "deny" will be denied (including if it is also in "allow") and any extension not in "allow" will be denied.


  • FormBuilder.Validator.FVUnauthorizedExtensions
  • FormBuilder.Validator.FVAuthorizedExtensions
  • FormBuilder.Validator.FVAuthorizedExtensions.[name_of_your_extension_group]
    • Example : FormBuilder.Validator.FVAuthorizedExtensions.PDF