Merge api call return 500

Which product are you using?
I’m using PDFjs version : “@pdftron/pdfjs-express”: “^8.4.0”

Detailed description of issue
We’re using /merge api call on our production server. We are uploading document first on s3 bucket and then we’re passing url to the /merge api call. One customer has issue when his Chrome browser call /merge api call and response is 500.

Expected behaviour
/merge api call need to return 200

Does your issue happen with every document, or just one?
Just on some complex document’s and only one customer has that issue for now. If I try to sign that same document i have 200 in response.

Link to document
Naples Plumbing.pdf (2.4 MB)
Uploading: Naples Mechanical.pdf…

Code snippet

const mergeAPI = (data) => {
  return new Promise((resolve, reject) => {
    fetch('', {
      method: 'post',
      body: data
      .then((response) => {
        if (response.status === 200) {
          return resolve(response.json());
        } else {
          response.text().then((text) => {
            reject({ status: response.status, message: JSON.parse(text) });
      .catch((error) => {