Hi

I have the forms &list module version 5.1.3 in DNN 5.5.1.

The form list shows fine for logged in users. But in settings if i enable the permission for "Create Record/ Submit Form" option for all users or Unauthenticated Users, it shows below error message  for anonymous users.

"A critical error has occurred.
Object reference not set to an instance of an object."

I just created the form with only one field to ensure that it has no illegal characters. But it still throws error message. 

Please can anyone help me to fix the issue?

Thanks
Dilip

I have the exact same problem.  
Here's what I find in the log:
ModuleId: 483
ModuleDefId: 123
FriendlyName: Inschrijving voor een Evenement
ModuleControlSource: DesktopModules/UserDefinedTable/Default.ascx
AssemblyVersion: 5.6.0
PortalID: 2
PortalName: EnduroFun
UserID: -1
UserName: 
ActiveTabID: 117
ActiveTabName: Inschrijving
RawURL: /EnduroFun/Inschrijvingsformulieren/Inschrijving/tabid/117/language/en-US/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: http://www.endurofun.be/Evenementen/Offroadcursussen/tabid/108/language/en-US/Default.aspx
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: fc95c968-9284-429a-81f5-012da8f984bd
InnerException: Object reference not set to an instance of an object.
FileName: 
FileLineNumber: 0
FileColumnNumber: 0
Method: DotNetNuke.Modules.UserDefinedTable.Security.ModuleSecurity.HasAddPermissonByQuota
StackTrace: 
Message: DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Modules.UserDefinedTable.Security.ModuleSecurity.HasAddPermissonByQuota(DataTable FieldsTable, DataTable DataTable, Int32 userRecordQuota, String username) at DotNetNuke.Modules.UserDefinedTable.EditForm.CheckPermission(Boolean isUsersOwnItem) at DotNetNuke.Modules.UserDefinedTable.EditForm.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---
Source: 
Server Naam: SERVER

Hi

In module settings i have applied a value for "Max. Records per User". I just removed it. It fixed the issue.

Regards
Dilip