vercel/ai · error · UnsupportedFunctionalityError

text file parts

Error message

text file parts

What it means

Perplexity only accepts binary/remote file content (e.g. PDFs by URL or data), not files whose payload is textual content carried inline. convertToPerplexityMessages throws UnsupportedFunctionalityError for file parts with data.type === 'text' since there is no corresponding Perplexity message field.

Source

Thrown at packages/perplexity/src/convert-to-perplexity-messages.ts:54

        const messageContent = content
          .map((part, index) => {
            switch (part.type) {
              case 'text': {
                return {
                  type: 'text',
                  text: part.text,
                };
              }
              case 'file': {
                switch (part.data.type) {
                  case 'reference': {
                    throw new UnsupportedFunctionalityError({
                      functionality: 'file parts with provider references',
                    });
                  }
                  case 'text': {
                    throw new UnsupportedFunctionalityError({
                      functionality: 'text file parts',
                    });
                  }
                  case 'url':
                  case 'data': {
                    const topLevelMediaType = getTopLevelMediaType(
                      part.mediaType,
                    );

                    if (topLevelMediaType === 'application') {
                      const fullMediaType = resolveFullMediaType({ part });

                      if (fullMediaType !== 'application/pdf') {
                        throw new UnsupportedFunctionalityError({
                          functionality: `file part media type ${fullMediaType}`,
                        });
                      }

View on GitHub (pinned to 69428b1f8b)

Solutions

1. Send the content as a normal text part instead of a file part
2. Upload/host the document and pass it as a URL file part (PDF)
3. Convert the text into a base64 data part with the proper media type if the content is a supported binary format

Example fix

// before
{ type: 'file', data: { type: 'text', value: 'document text...' }, mediaType: 'application/pdf' }
// after
{ type: 'text', text: 'document text...' }

for (const part of msg.content) {
  if (part.type === 'file' && part.data?.type === 'text') {
    throw new Error('Send textual content as a text part, not a file part (Perplexity)');
  }
}

function isTextFilePart(part: { type: string; data?: { type?: string } }): boolean {
  return part.type === 'file' && part.data?.type === 'text';
}

try {
  await generateText({ model: perplexity('sonar-pro'), messages });
} catch (e) {
  if (UnsupportedFunctionalityError.isInstance(e) && e.message.includes('text file parts')) {
    // convert those parts to plain text parts and retry
  } else throw e;
}

When it happens

Trigger: Constructing a file part with data as plain text/string content ({ type: 'text', ... }) in a message sent to a Perplexity chat model.

Common situations: Passing extracted text of a document as a 'file' part instead of as a text part; generic document pipelines that build file parts with inline text payloads regardless of provider.

Related errors

• file parts with provider references
• file part media type ${fullMediaType}
• AI_UnsupportedFunctionalityError
• file parts with provider references
• File URL data

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/1ee64efb30f32886. Report an issue: GitHub.