‎Word Desktop: Add‑in cannot create new document from template (regression, backend call succeeds)‎

[desertfireadmin]

Summary

Word Desktop appears to fail to create/open a new document from a template via our Office.js Word add-in after updating to Word Version 2505 (Build 18827.20128, Click-to-Run). The add-in loads and authenticates successfully, and the backend template request succeeds (HTTP 200 with non-trivial payload), but Word does not create/open the new document.

This worked prior to the Word update, and no add-in/backend changes were deployed.

Product / Platform

• Host: Microsoft Word (Desktop)
• Platform: Windows (Click-to-Run)
• Office / Word Version: 2505
• Build: 18827.20128
• Add-in type: Task pane add-in (Office.js)
• office.context.diagnostics

{host: 'Word', version: '16.0.18827.20128', platform: 'PC'}

Expected behavior

Selecting a template in the add-in should create/open a new Word document based on the template.

Actual behavior

The template download succeeds, but Word fails to create/open the new document. Behavior may be silent (no new document) or results in a generic failure during the insertion/open step.

Repro steps

1. Open Microsoft Word Desktop (Version 2505, Build 18827.20128).
2. Open our Word task pane add-in.
3. Log in (auth succeeds).
4. Choose "Create new document from template" (template stored in backend).
5. Observe that the backend template request completes successfully (HTTP 200, payload ~42–58 KB).
6. Word fails to open/create the new document.

Diagnostics / Evidence

• Network trace from Edge DevTools attached to the task pane shows repeated requests like:
  template?name=<guid>-ClassicSide.docx
  • Status: 200
  • Type: XHR
  • Response sizes observed: ~42.4 KB and ~58.6 KB
  • Preflight requests succeed (CORS appears OK)
• Clearing Office add-in cache:
  %LOCALAPPDATA%\Microsoft\Office\16.0\Wef
  did NOT resolve the issue.
• Workaround: Opening an existing document created previously from the template and then using the add-in to edit works as expected.
• Error log:
  main.69c897e25604f0788cbd.js:1 ERROR Error: Uncaught (in promise): TypeError: Cannot read properties of undefined (reading '_marketplaceType')
  TypeError: Cannot read properties of undefined (reading '_marketplaceType')
  at Object.value [as set] (word-win32-16.01.js:25:181241)
  at e. (main.69c897e25604f0788cbd.js:1:2332392)
  at main.69c897e25604f0788cbd.js:1:339783
  at Object.next (main.69c897e25604f0788cbd.js:1:339888)
  at a (main.69c897e25604f0788cbd.js:1:338630)
  at e.invoke (polyfills.068996c408ed4139cf2f.js:1:7310)
  at Object.onInvoke (main.69c897e25604f0788cbd.js:1:270627)
  at e.invoke (polyfills.068996c408ed4139cf2f.js:1:7250)
  at t.run (polyfills.068996c408ed4139cf2f.js:1:2410)
  at polyfills.068996c408ed4139cf2f.js:1:14331
  at e.invokeTask (polyfills.068996c408ed4139cf2f.js:1:7994)
  at Object.onInvokeTask (main.69c897e25604f0788cbd.js:1:270510)
  at e.invokeTask (polyfills.068996c408ed4139cf2f.js:1:7915)
  at t.runTask (polyfills.068996c408ed4139cf2f.js:1:3073)
  at _ (polyfills.068996c408ed4139cf2f.js:1:10310)
  at t.invokeTask [as invoke] (polyfills.068996c408ed4139cf2f.js:1:9155)
  at g (polyfills.068996c408ed4139cf2f.js:1:22175)
  at EmbeddedBrowserWebView.y (polyfills.068996c408ed4139cf2f.js:1:22408)
  at Object.value [as set] (word-win32-16.01.js:25:181241)
  at e. (main.69c897e25604f0788cbd.js:1:2332392)
  at main.69c897e25604f0788cbd.js:1:339783
  at Object.next (main.69c897e25604f0788cbd.js:1:339888)
  at a (main.69c897e25604f0788cbd.js:1:338630)
  at e.invoke (polyfills.068996c408ed4139cf2f.js:1:7310)
  at Object.onInvoke (main.69c897e25604f0788cbd.js:1:270627)
  at e.invoke (polyfills.068996c408ed4139cf2f.js:1:7250)
  at t.run (polyfills.068996c408ed4139cf2f.js:1:2410)
  at polyfills.068996c408ed4139cf2f.js:1:14331
  at e.invokeTask (polyfills.068996c408ed4139cf2f.js:1:7994)
  at Object.onInvokeTask (main.69c897e25604f0788cbd.js:1:270510)
  at e.invokeTask (polyfills.068996c408ed4139cf2f.js:1:7915)
  at t.runTask (polyfills.068996c408ed4139cf2f.js:1:3073)
  at _ (polyfills.068996c408ed4139cf2f.js:1:10310)
  at t.invokeTask [as invoke] (polyfills.068996c408ed4139cf2f.js:1:9155)
  at g (polyfills.068996c408ed4139cf2f.js:1:22175)
  at EmbeddedBrowserWebView.y (polyfills.068996c408ed4139cf2f.js:1:22408)
  at w (polyfills.068996c408ed4139cf2f.js:1:13570)
  at polyfills.068996c408ed4139cf2f.js:1:14387
  at e.invokeTask (polyfills.068996c408ed4139cf2f.js:1:7994)
  at Object.onInvokeTask (main.69c897e25604f0788cbd.js:1:270510)
  at e.invokeTask (polyfills.068996c408ed4139cf2f.js:1:7915)
  at t.runTask (polyfills.068996c408ed4139cf2f.js:1:3073)
  at _ (polyfills.068996c408ed4139cf2f.js:1:10310)
  at t.invokeTask [as invoke] (polyfills.068996c408ed4139cf2f.js:1:9155)
  at g (polyfills.068996c408ed4139cf2f.js:1:22175)

Additional diagnostics

Word API used
Our add-in creates new documents from templates using the Word API:
Document.insertFileFromBase64(...)

This was confirmed by inspecting the loaded Word runtime sources in DevTools
(searching for insertFileFromBase64 in word-win32-16.0.1.js and related files).

Template payload format
Templates are delivered as Base64 and passed directly to
Document.insertFileFromBase64 (not OOXML, not binary open).

Observation
Backend retrieval succeeds (HTTP 200 with non-trivial payload), and failure occurs
after Base64 is handed to Word for insertion, indicating a Word document
creation/insertion regression rather than a backend or add-in retrieval issue.

Impact

Customers cannot create new PPM documents from templates via the add-in on this Word build. Editing existing documents works, but this is not a viable long-term solution.

Notes / Hypothesis

This appears to be a Word Desktop regression affecting the document creation/template insertion step (e.g., Document.insertFileFromBase64 or related flow). Backend retrieval succeeds; failure occurs after retrieval when Word attempts to open/insert the template.

Additional note: As a workaround, opening an existing document and then using the
add-in to insert/update content works as expected. The failure only occurs when
creating a new document via Document.insertFileFromBase64.

Additional info requested

• Is Word Version 2505 / Build 18827.20128 known to have regressions impacting Word add-ins that create new documents from templates?
• Are insertFileFromBase64 APIs impacted on this build?
• Any recommended mitigations while waiting for an Office fix?

Attachments

• Screenshot of DevTools Network tab showing 200 responses and payload size.
• (Can provide) minimal repro add-in if needed (template download + insert call).
  `` video showing what happens: [https://go.screenpal.com/watch/cOe1cMnZFJG]

[github-actions]

This issue was automatically labeled as a regression based on dual-LLM analysis of the issue content and comments.

Reason: The issue is described as a regression in the title and throughout the description. The functionality of creating a new document from a template using the Office.js Word add-in worked prior to the update to Word Version 2505 (Build 18827.20128). The add-in and backend have not changed, indicating that the issue is likely due to the Word update. The error occurs after the backend successfully retrieves the template, suggesting the problem lies in the Word application's handling of the document creation process, specifically with the Document.insertFileFromBase64 API. The presence of a TypeError in the error logs further supports the likelihood of a regression caused by the update.

[junaid042]

@desertfireadmin insertFileFromBase64 means you are inserting a new word document in your current opened document.

Use createDocument method for creating new documents hopefully this will help you!

 // Link to full sample: https://raw.githubusercontent.com/OfficeDev/office-js-snippets/prod/samples/word/50-document/insert-external-document.yaml

// Updates the text of the current document with the text from another document passed in as a Base64-encoded string.
await Word.run(async (context) => {
  // Use the Base64-encoded string representation of the selected .docx file.
  const externalDoc: Word.DocumentCreated = context.application.createDocument(externalDocument);
  await context.sync();

  if (!Office.context.requirements.isSetSupported("WordApiHiddenDocument", "1.3")) {
    console.warn("The WordApiHiddenDocument 1.3 requirement set isn't supported on this client so can't proceed. Try this action on a platform that supports this requirement set.");
    return;
  }

  const externalDocBody: Word.Body = externalDoc.body;
  externalDocBody.load("text");
  await context.sync();

  // Insert the external document's text at the beginning of the current document's body.
  const externalDocBodyText = externalDocBody.text;
  const currentDocBody: Word.Body = context.document.body;
  currentDocBody.insertText(externalDocBodyText, Word.InsertLocation.start);
  await context.sync();
});

[davidchesnut]

Hi @desertfireadmin, this issue looks very similar to #6552. That issue was fixed today, so can you please check to see if the problem still occurs?

Thanks!
David

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This issue has been automatically marked as stale because it is marked as needing author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment. Thank you for your interest in Office Add-ins!

[microsoft-github-policy-service]

This issue has been closed due to inactivity. Please comment if you still need assistance and we'll re-open the issue.