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How to troubleshoot prefilling issues in miniExtensions Form?
How to troubleshoot prefilling issues in miniExtensions Form?

I need to prefill multiple fields in a form. When I submit it, the prefilled fields are not saved to Airtable.

Updated over a week ago

If you're having trouble, check the following:

1. Incorrect parameter syntax (most common)

The prefill function in miniExtensions Form works in the same way that Airtable Form does. In many cases, the issue is within the URL itself.


Here's how to prefill more than one option in a multi-select field by separating the values by commas.

Example A,z

Example B

Bad syntax examples:

A. Special characters are not encoded properly.

B. The parameter ‘prefill_’ is not repeated in every field.

C. Field names are case-sensitive. Also, it has to match the actual field name in Airtable, not the custom title you have in the form.

D. Commas in linked records have to be wrapped in quotes. If the value itself has a comma, it has to be wrapped even if the comma is encoded as %2C. Example:


Value A: some, test
Value B: box

Test in Airtable Form

Try the syntax in an Airtable Form and see if it works first.

If you’re still having the problem and unable to reproduce the prefilling issue with Airtable Form too, unfortunately, we can't help with troubleshooting issues that are not caused by miniExtensions.


Using the ENCODE_URL_COMPONENT function in Airtable helps minimize improper syntax errors. If you need to figure out the proper way to prefill, many experts in the Airtable forum might be able to help. We would be able to investigate anything related to the miniExtensions setup.

2. Field Filters

Another reason could be the field's validation rules. Make sure that the value you're trying to prefill is 'selectable' if you try to add it to the form manually.

3. The field is read-only

If the field is set to read-only, that will cause prefilling to not work. Prefilling is a form of editing. You must enable the "Allow URL prefills" toggle to allow it for read-only fields.

4. Hidden fields

If the prefill fields are not part of the form, enable prefilling hidden fields.

⚠️ Potential Edge Case

If you went through the steps above and the field is successfully being prefilled in Airtable Form, but not in miniExtensions, please submit a report to our support team to look into it. Make sure to include:

1. miniExtensions Form URL

2. Airtable Form URL


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