You filled in every field. Tabbed through carefully. Hit save. Closed the file. Reopened it — and it's blank again.
Form data didn't make it into the saved file. There's a reason, and there's a workaround.
What's actually going wrong
Two main causes. Reader-only form. The PDF was created with restrictions saying 'fillable but not saveable' — common in older Acrobat workflows and some government forms. Filling in the fields works; saving with data filled-in doesn't. Save-as fail. The viewer saved a flattened copy that visually shows the fields but technically doesn't store the data, then the next opener sees the underlying empty template.
The second one is the more common cause and the easier fix.
The quick fix
Fill the form, then 'flatten' it. Flattening merges the field values into the page itself, turning your filled form into a permanent finalised PDF with the data baked in.
In Flint, open the form in edit PDF, fill the fields, and use 'Save as flat PDF'. The output is a regular PDF where what you see is what's saved — no fields, no template, no resetting.
If that didn't work
For genuinely reader-only forms, the workaround is to print-to-PDF after filling. The print pipeline rasterises everything, fields included, and the saved output is permanent.
Alternatively, convert the filled PDF to JPG and back to PDF — the conversion bakes in the field values.
For forms you fill regularly, ask the issuer for a non-restricted version. There's almost never a good reason for 'fillable but not saveable' and most issuers will provide an open version on request.
Prevent it next time
Always flatten forms after filling. Don't just save — flatten. Most PDF tools default to keeping the form layer editable; force a flatten step before closing. And for important submissions, save both a flattened copy (for your records) and an editable copy (in case you need to update before sending).
FAQ
What does 'flatten' mean for a PDF form?
Flattening converts editable form fields into permanent text on the page. After flattening, the form looks identical but the fields are no longer interactive — and the data is now part of the file rather than overlay state.
Why does some viewer say 'fields will not be saved'?
The form is marked reader-only. The viewer is warning that you can fill it but the values will be discarded on save. Flatten before saving to keep the data.
Can I save a partially-filled form?
Yes — flatten partial completion if you want a record, or use a viewer that supports saving editable forms (Flint's editor does). Just don't rely on plain save in restricted viewers.
Why do I lose form data when I email a PDF?
If your viewer saved a copy with editable fields rather than flattening, and the recipient's viewer doesn't support saved form state, they see a blank form. Flatten before sending to remove the dependency.
Filled forms need to be flattened. Edit your PDF in Flint, flatten on save, and the data stays put for everyone who opens it.