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日本語First, work out which case you are in
Searches for "word translation not working" cover rather different errors. Match your case in the three rows below, then start from that section:
| Symptom | Common cause | Try first |
|---|---|---|
| "Service not available" | Network / proxy, firewall, service temporarily unavailable, document too large | §3 network → §4 small-document test → §5 splitting |
| "Translate Document" fails / Document translation failed | Page limit exceeded, TOC fields or links, an individual file damaged | §5 splitting → §6 clean copy |
| Translate button greyed out, no Translate in the menu | No text selected, Protected View, add-in conflict, not signed in | §7 environment and add-ins |
Case study: a 129-page thesis that failed even with a working connection
We opened a Microsoft Office LTSC Professional Plus 2021 Word document: a 129-page, 70,000+ character degree thesis (.docx), and used Review → Translate → Translate Document. The "Translator" panel on the right kept showing a red message at the top:
Service not available. Please check your connection and try again.
At that point the browser could open external sites normally and the system network showed as connected; turning the VPN on or off made no difference to full-document translation. This does not contradict the usual advice in the Microsoft community to "check the network first" — besides the network, document size and complexity are equally common triggers.
Splitting the appendices out of the original into small files (for example a single one-page "Appendix A"), on the same computer and the same Word version, "Translate Document" (full-document translation) and "Translator → Select" both return translations normally; the screenshot below uses selection mode after selecting a heading:
Conclusion: for long documents, built-in translation sometimes fails with "service not available", which is easily mistaken for a pure network problem; splitting into 1–2 page files and translating them one by one is the workaround we verified, but merging them back still needs manual work on formatting and cross-references.
Why Word built-in translation so often stops working
- It depends on an online service: translation in Review runs through Microsoft's cloud, so the machine must reach the relevant domains; a corporate proxy, a wrong global VPN or an outdated TLS version can all break the connection.
- Each request has a size limit: several users in the Microsoft community report that full-document translation starts failing at around 100 pages ; an official reply suggests staying within 40 pages. TOC hyperlinks and complex field codes lower the practical limit further.
- Individual files can be damaged: when only one .docx fails and others are fine, the cause may be confused language tags, Protected View or hidden corruption; test with a "clean copy" (see §6).
- Office components or add-in conflicts: third-party translation add-ins, COM add-ins or an outdated Office installation can grey out the button or stop features from loading.
Step 1: check the network and proxy (about 10 minutes)
The steps below come from the official Microsoft community and common IT practice. After each change, test "Translate Document" with a new one- or two-page document first; do not immediately retest with a hundred-page file.
- Check the proxy: press
Win + R→ typeinetcpl.cpl→ "Connections" → "LAN settings" and clear "Use a proxy server for your LAN" (unless your company requires a proxy). - Enable TLS 1.2: still in Internet Options → "Advanced", tick "Use TLS 1.2" (and 1.1 / 1.0 depending on the system), apply and restart the computer.
- Turn off the VPN temporarily: if you use a VPN, exit it completely and retest; if small documents then translate but long ones still fail, it is more likely a size problem than a routing problem.
- Check the firewall: make sure Word / Office is not blocked from making outbound connections.
- Reset Winsock (optional): run this in an administrator command prompt
netsh winsock resetand restart (try it when the network misbehaves).
Step 2: use a "small document" to tell network and document problems apart
- Create a blank Word document and paste two or three Chinese or English paragraphs.
- Review → Translate → Translate Document, choose the target language and click "Translate".
- Small document works, long document fails → split it first (§5); do not keep fighting the network.
- Small document fails too → repair Office (§7), or switch to Word for the web and office.com upload it to try translating (some users report a different limit there).
Step 3: split long documents into 1–2 page files (the built-in workaround)
If you must keep using Word's built-in translation and do not want an add-in, split the main document into small files by chapter:
- Use the Navigation Pane with "Heading 1 / Heading 2" to see the chapter boundaries.
- Select one section (keep it to 1–2 pages where possible), copy it into a new document and save it as a separate .docx.
- Use "Translate Document (full-document translation)" or "Translate Selection" on the small file; in our test, with an appendix of only one page, both modes returned results reliably.
- After translating each part, paste the translation back into the right place in the main document and check by hand the heading numbers, table of contents, cross-references and page numbers.
Community experience also suggests that if a document has an automatic table of contents, pasting the TOC as plain text before translating can sometimes raise the page limit — but for a hundred-page thesis it may still not be enough, and splitting is safer.
Step 4: make a clean copy of a single "bad file"
If only one file fails, follow the Microsoft community advice for single-file failures:
Ctrl + ASelect all → Review → Language, set the correct document language and turn off unnecessary automatic detection.- Create a blank document → Home → Paste → Keep Text Only to remove unusual formatting and fields.
- Save under a new file name and try translating again (some layout is lost; use this only to test whether the file is damaged).
Step 5: repair Office and add-ins
- Update Office: File → Account → Update Options → Update Now.
- Online repair: Settings → Apps → Installed apps → Microsoft Office → Modify → Online repair (more thorough than a quick repair).
- Reset the template (optional): close Word, back up and delete
%appdata%\Microsoft\Templates\Normal.dotmthen restart (this affects custom styles; use with care). - Sign in to your Microsoft account again: File → Account, sign out and sign in again (a common check for subscription versions).
Do not want to split again and again? Handle the whole document with a Word translation add-in
Splitting is expensive for long documents such as theses, contracts and bids: many chapters and cross-references mean the layout easily breaks when merging. If your goal is to translate inside the original document and keep the layout as far as possible, install a dedicated Word translation add-in and translate the whole document or part of it in the sidebar, instead of copying the text into a web page and pasting it back.
Word translation add-in provides:
- Full-document translation : scans long documents paragraph by paragraph and writes back in place — suited to hundred-page manuscripts (see the product notes for current limits), with no need to split into dozens of one-page files.
- Selection translation : translate only one chapter or a few items; anything not selected stays untouched.
- Selected-text translation : select text to see its translation without changing the document by default, so you can read first and decide whether to write back.
- Glossaries : keep proper nouns consistent, so a long document does not drift in terminology.
Install: download the TopCopilot installer on Windows → close Word → install → reopen Word, then open the sidebar from the "AI assistant" tab in the ribbon. The same installer also supports Excel / WPS. See the Word translation add-in and official download page.
Quick comparison: Word built-in translation vs TopCopilot
| Aspect | Word: Review → Translate | TopCopilot sidebar |
|---|---|---|
| Long documents (e.g. 100+ pages) | Prone to failure, or needs splitting into 1–2 page files | Full-document translation works paragraph by paragraph, no manual splitting |
| Formatting preservation | Full-document translation opens a copy in a new window; merging split files is manual | Writes back inside the original document, keeping lists, tables and more |
| Terminology consistency | No built-in glossary | Glossaries keep translated terms consistent |
| cost | Available with an Office subscription or volume licence | Free trial + subscription allowance (see pricing) |
FAQ
Does "service not available" in Word always mean a network problem?
Not always. Beyond the network, proxy and firewall, a document that exceeds what the built-in service can process, broken field codes or table-of-contents links, or damaged Office components can trigger the same error. Check the network first, then try a new small document and split the long one.
How many pages can Word full-document translation handle?
Microsoft's community reports no single official limit; in practice it is often around 40–100 pages, and documents with complex layout, TOC links or many figures hit the limit earlier. If full-document translation fails, split the file into 1–2 page pieces and translate them one by one, or use a third-party add-in that works through the document in sections.
Does a VPN fix Word translation?
It helps some users (especially when the proxy configuration conflicts), but it is no cure-all. In our test, with the browser able to reach the internet, the 129-page thesis still reported that the service was unreachable, and built-in translation only recovered after splitting it into small documents. Try removing the system proxy first; if that does not help, look at the document size.
Word built-in translation only works paragraph by paragraph. Is there a way to translate the whole document and keep the formatting?
You can install a Word translation add-in that preserves formatting. TopCopilot translates the whole document in the sidebar, scanning paragraph by paragraph and writing back in place, keeping headings, lists, tables and cross-references as far as possible.
Why is the Word translate button greyed out?
Common causes: no translatable text selected, the document is protected or read-only, an add-in conflict, or Office is not signed in to a Microsoft account. Test with a new blank document, check the Review → Translate entry point, and disable third-party COM add-ins under Options → Add-ins before restarting Word.
