During flatten, expected instance of PDFDict or PDFStream, but got instance of undefined

Hello!

I’m encountering the following crash when trying to flatten a W4 from the IRS’ website.

/home/ubuntu/src/x/node_modules/pdf-lib/cjs/core/errors.js:38
this = _super.call(this, msg) || this;
^
Error: Expected instance of PDFDict or PDFStream, but got instance of undefined
at new UnexpectedObjectTypeError (/home/ubuntu/src/x/node_modules/pdf-lib/cjs/core/errors.js:38:24)
at PDFContext.lookup (/home/ubuntu/src/x/node_modules/pdf-lib/cjs/core/PDFContext.js:93:15)
at PDFDict.lookup (/home/ubuntu/src/x/node_modules/pdf-lib/cjs/core/objects/PDFDict.js:64:48)
at PDFWidgetAnnotation.PDFAnnotation.getAppearances (/home/ubuntu/src/x/node_modules/pdf-lib/cjs/core/annotation/PDFAnnotation.js:89:20)
at PDFTextField.needsAppearancesUpdate (/home/ubuntu/src/x/node_modules/pdf-lib/cjs/api/form/PDFTextField.js:670:48)
at PDFForm.updateFieldAppearances (/home/ubuntu/src/x/node_modules/pdf-lib/cjs/api/form/PDFForm.js:534:23)
at PDFForm.flatten (/home/ubuntu/src/x/node_modules/pdf-lib/cjs/api/form/PDFForm.js:450:18)
at file:///home/ubuntu/src/x/fillOut.js:293:6

Using v1.16.0, any suggestions to workaround this issue?

My code adds a bunch of text (it doesn’t use the Form API, just writes at given coordinates), and then flatten the PDF using PDFForm.flatten().

[NoNameProvided]

It also worked for me to “touch” all field via setting an empty text as value inside:

const pdfDoc = await PDFDocument.load(pdfDocBytes);
const form = pdfDoc.getForm();
const fields = form.getFields();

fields.forEach(field => form.getTextField(field.getName()).setText(''));

// Form flatten works now as expected.
form.flatten();

[Hopding]

Please fill out the new bug report form if you’re still having trouble with this.