I have integrated the Webflow form with Mailchimp using the Make app. I have completed this process, and everything is working correctly when I test it.
What is the problem & what have you tried?
When my client or their client tests the form by adding or submitting a form, only the email is added to the Mailchimp list, while the other fields remain empty. However, in my Webflow form submissions, all the entries appear correctly in the backend. I want to fix this issue because it returns a 400 error that I shared earlier.
I have researched this error message thoroughly, but either I have already implemented the suggested solutions or they were not relevant. The submitted data with the error shows no fields filled. However, when I resend that submission, the lead is sent successfully with all the data visible.
What have you tried so far?
I have mapped the fields again.
The add/update subscriber module is already in use.
Emails that are entered but show as empty in Mailchimp are not in the archived list.
When I test from my end, the leads are successfully sent to Mailchimp. However, when clients use the form, the leads are not sent—only the email and tag are passed.
It sounds like the issue may be happening before the Mailchimp step rather than inside Mailchimp.
Since resending the same bundle works, I would compare a failed run and a successful run in Make and look at the output from the Webflow module first. If those fields are already empty there, Mailchimp is only receiving incomplete data.
A couple of things worth checking are whether the Webflow form field names changed after the module was first mapped, whether the client is submitting through a different version of the form, and whether refreshing or remapping the Webflow fields in Make pulls the correct structure again.
Dr. Tanvi Sachar
Monday Certified Partner, Tuesday Wizard
I have checked my Webflow module, and the fields are appearing correctly there (see image: webflow-module).
In the Mailchimp module, the input bundle is also visible. However, an error appears in the output (see image: mailchimp-module).
Points I have already verified:
The Webflow form fields names have not been changed.
There is no other version of the same form.
The mapping has been remapped and rechecked multiple times.
Question regarding the error message:
When the error occurs and I resubmit the same entry, the submission gets updated successfully. This suggests that the Update module is working correctly. Additionally, when I test the form normally, the submissions are added successfully.However, sometimes an error appears and the entry is not added to Mailchimp. Because of this inconsistent behavior, I would like to understand why the error occurs even though the modules appear to be configured correctly.
The error message actually gives a clue about what’s happening. Mailchimp is saying the email is already a member of the list. That means when the module runs, Mailchimp already has that contact.
From your run log it looks like there are several “Add/Update Subscriber” modules and some bundles are being stopped by filters. If more than one path tries to process the same email, one request can hit Mailchimp first and create the contact, while the next request then tries to create it again and Mailchimp returns that error.
That would also explain why resending the same submission works. By then the contact already exists in the audience, so the module simply updates it instead of trying to create it.
I would check whether more than one Mailchimp module can run for the same submission, or whether the router filters allow multiple paths for the same email. If the goal is just to create the contact and assign data like tags or fields, it’s usually simpler to create or update the subscriber once and then handle the rest of the logic after that step.
Dr. Tanvi Sachar
Monday Certified Partner, Tuesday Wizard
The reason for using all of this setup is to collect submissions in Mailchimp as well as send the submission emails to a specific email address.
In this scenario, there are multiple modules for multiple forms, and each form has its own unique filter that the other forms do not have. When we manually send a submission by clicking the “Run Once” button, the flow follows only the path assigned to that specific form. If multiple paths were triggered by the same email, the log would show all the paths followed. However, as shown in the image below, only the filter assigned to that form was active.
What I want to emphasize is that many times the process works successfully, but sometimes an error occurs. When the error happens, the log shows that it follows only the path for that specific form, not multiple paths.
From the screenshot and the error message, it looks like the issue is coming from Mailchimp rather than the routing logic in your scenario.
The error says the email is already a list member. This usually happens when Mailchimp receives a request to create a subscriber that already exists in the audience. When that happens, Mailchimp rejects the request unless it is explicitly treated as an update.
Since your module is “Add/Update a Subscriber,” the most common cause is timing. Sometimes Mailchimp already has the contact by the time the request reaches it, especially if the same email was previously submitted or added from another source. When you resend the bundle, the contact already exists, so the module simply performs the update and succeeds.
Your router behavior in the logs looks correct. Only the intended path is running, so it does not appear that multiple filters are firing.
A couple of things you could check:
Make sure the option to create or update the subscriber is enabled so the module always performs an upsert rather than trying to create a new contact first.
Confirm that the same email is not being added to the audience by another integration, automation, or Mailchimp form at the same time.
If the error still appears occasionally, adding a simple error handler that retries the module or switches to an update step can help smooth out those intermittent cases.
Dr. Tanvi Sachar
Monday Certified Partner, Tuesday Wizard
What is your goal?
What is the problem & what have you tried?
What have you tried so far?
Screenshots (scenario flow, module settings, errors)
