I am running a new install of Umbraco version 8.0.1 with Umbraco Forms 8.1.1. I am able to create forms normally and they render as expected, however on submit it errors.

My original form was a basic contact form. I removed the "Yes, I give permission to store and process my data" question and added a recaptcha. Otherwise just a plain form. This form had a workflow to display a thank-you message and then send an email. The form is not using moderation.

When I would submit it, I would not see the thank you message, just refresh the page with a blank form. In the logs I saw the following

{"@t":"2019-04-23T01:50:35.8169065Z","@mt":"There was a problem sending an email to {Email} from Workflow for Form {FormName} with id {FormId} for Record with unique id {RecordId}","@l":"Error","@x":"System.NullReferenceException: Object reference not set to an instance of an object.\r\n at Umbraco.Forms.Core.Services.XmlService.ToXml(RecordField recordField, XmlDocument xmlDocument)\r\n at Umbraco.Forms.Core.Services.XmlService.ToXml(Record record, XmlDocument xd)\r\n at Umbraco.Forms.Core.Providers.WorkflowTypes.SendEmail.Execute(Record record, RecordEventArgs e)","Email":"[email protected]","FormName":"Contact form","FormId":"b2ed8850-52a7-49e4-9bbd-a5cbd6322d34","RecordId":"25aa305d-27df-4c21-9b29-8ee4425a1ff9","SourceContext":"Umbraco.Forms.Core.Providers.WorkflowTypes.SendEmail","ProcessId":68548,"ProcessName":"w3wp","ThreadId":171,"AppDomainId":9,"AppDomainAppId":"LMW3SVC211ROOT","MachineName":"A2NWVPWEB115","Log4NetLevel":"ERROR","HttpSessionId":"dfszx3ickdtatgsfhg14n5pr","HttpRequestNumber":7,"HttpRequestId":"312bad58-90a7-4002-88ff-cbd29e073306"}

After much fussing with email settings, I finally removed the email step from the workflow but still no thank you message. Then I removed the recaptcha, still nothing. The submission does get created in the Form Entries and the redirect does seem to work. I could live with just setting a thank you page and redirecting, that's fine. But I have to get the email piece working.

So far I have tried reinstalling Forms, deleting/recreating the form, verified my recaptcha keys, tried with anti-forgery on & off, re-built the models (I am running in "Dll" mode), I've changed themes, removed all custom styles, I am just stumped. The site is running on GoDaddy, but I have many other Umbraco sites on GoDaddy with Umbraco Forms and it has always worked fine. I've verified FullTrust, verified my smtp setting match GoDaddy's recommended settings of using their relay.

Could this be to do with using "Dll" mode?

Thanks -Roger