Costum UI Jira add pdf attachment

I’m trying to add a PDF document as an attachment that I download from my server. I either get the 415, unsupported media type, or the TypeError: function () { [native code] } could not be cloned. error. I have seen this problem on this forum, like here or here. I have even found this, where it was stated that this issue had been fixed already and released in forge/bridge 2.6. I made sure to refresh my project so it would use 2.6. It didn’t resolve my issue unfortunately. I’m using forge/api@2.11.0, forge/resolver@1.4.10, forge/bridge@2.6.1

Note that this code doesn’t use my PDF file, instead a FormData variable:

resolver.define('uploadToTicket', async ({ payload }) => {

  const form = new FormData();
  form.append('file', 'file');
  form.append('fileName', 'test');
  form.append('fileName', 'comment');
  form.append('minorEdit', 'true');

  const result = await api.asUser().requestJira(route`/rest/api/2/issue/${payload.issueKey.issueKey}/attachments`, {
    method: 'POST',
    body: form,
    headers: {
      'Accept': 'application/json',
      'X-Atlassian-Token': 'no-check',
  if (result.ok) {
    console.log("Attachment upload ok");
  else {

I have also tried to download a PDF attachment from a Jira ticket and reupload it, using the REST API response’s text() or arrayBuffer() function, with no success.

Could you help me resolve the issue?


Can you assist me on this matter?

Best regards,