In my case, not that you can see from the inputs. It could be that registrants are entering special characters that aren't passing over to Marketo, like accent marks on names. Read yesterday that many forms struggle with Spanish names. One of the names that was definitely breaking the integration over the weekend was Mondragon. No visible atypical characters, but when I tried to reregister the lead, integration broke and status came through as Registration Error. When I replaced only the lead's last name with my own (all other details and UTM used same), Registration Error updated to Registered and no integration break. So I then just overwrote Wilson in Marketo profile with Mondragon again. But not a long-term solution. Ideally lead will register for other things in future. Don't want then encountering this same headache of 'Am I registered? Where's my confirmation email?' every time! Too much friction in the UX.
I recently found this was an issue in GTW registrations from Marketo forms. I can confirm that the special character "|" or pipe, somehow breaks the form integration. After taking this out of the field, the registration API call works.
In my case it definitely wasn't a special characters issue. For example, the last name Mondragon kept breaking the API, even when I tried to register the lead manually with no special characters. At one point I tried registering the lead on the GTW side and last name box went red saying Last name required, even though I'd typed Mondragon in and it was visible in the field. Yet when I used all lead details, including email, and substituted my last name for lead's last name, registrations went through without error/causing disconnect. Then would update to their real details in Marketo DB (Note: this did create unexpected problems, as the lead later went on to a GoToMeeting call and was asked by an associate if she'd recently married/changed her last name, because GTM showed her as Wilson instead of Mondragon. Hadn't occured to me that my hack would overwrite her GTM profile).
We ran 4 webinars in January and were constantly dealing with this. Put in support call to Marketo but just felt like I got the runaround, asking me to do things I'd already done with a previous support person, not reading through my case thread on support handover, asking me to do things that were opposite of what I'd been asked to do. In end I just gave up replying cause it felt like they were just guessing. After 4 weeks it wasn't solved. I just had to sit with Launchpoint open in my browser all day and periodically refresh for peace of mind that it wasn't broken...plus set up the Alert Amy Connor mentions above.
I found this online and we did try ticking/unticking additional fields box in Launchpoint. Didn't seem to make a difference for us, but maybe we were unlucky: Extension is passing first name, last name and email only to Citrix, if other fields are marked as r...
Perhaps this is useful too? Help | Training | Salesforce
Maybe if we're using Marketo forms we should untick the Enable Additional Fields (Company Name, Job Title) box in Launchpoint and make sure that ONLY names and email fields are ticked on the Citrix/GTW side in the Registrations tab?