Fix: Compare Documents Not Working in Word

The Problem

Word’s Compare Documents feature isn’t working. You try to go to Review > Compare > Combine, select two files, but nothing happens or an error appears. The comparison dialog hangs or closes without creating comparison. You need to see all differences between two versions but Word’s Compare feature is broken. Files are incompatible format or the feature can’t find them.

Quick Fix

Ensure both documents are saved and closed:

1. Save both documents you want to compare: Press Ctrl+S in each
2. Close all Word documents: File > Close All
3. Go to Review tab in ribbon
4. Click Compare (dropdown arrow next to Compare button)
5. Select Compare or Combine (Combine is for merging edits)
6. In the dialog:
   • Original document: Browse to your first document
   • Revised document: Browse to your second document
7. Click OK (not “More Options” for now)
8. Wait 10-30 seconds (comparison takes time for large documents)
9. A new document opens showing all differences as tracked changes

If this doesn’t work, proceed to Step-by-Step Solution.

Step-by-Step Solution

Step 1: Close All Open Word Documents

Open documents interfere with Compare function.

1. Close all Word documents:
   • File > Close All or close each individually
2. Verify Word window is empty
3. Don’t close Word itself—keep the application open
4. Now open Compare function: Review > Compare > Compare

Step 2: Choose Correct Document Locations

Files must be saved before comparing.

1. In Compare dialog, click “Original document” folder icon
2. Navigate to where your first document is saved
3. Double-click the file to select it (or click once and click “Open”)
4. Important: Don’t open the file—just select it
5. The filename appears in the “Original document” field
6. Now click “Revised document” folder icon
7. Navigate to your second document
8. Select it the same way
9. Both filenames now show in the dialog
10. Click OK

Step 3: Check File Compatibility

Documents must be in compatible formats.

1. Both files should be:
   • Word documents (.docx, .doc, .docm)
   • Not PDF, not image, not other format
2. Verify file extensions:
   • Right-click each file > Properties
   • Check the “Type” field
   • Both should say “Microsoft Word Document” or similar
3. If one is PDF:
   • You can’t compare directly to PDF
   • Convert PDF to Word first (special tools required)
   • Or use alternative comparison method (Step 10)

Step 4: Verify Files Are Not Open or Locked

Files in use can’t be compared.

1. Check if documents are open:
   • If they are, close them (File > Close)
   • Don’t save if you don’t want to
2. Check if files are locked by another user:
   • Right-click the file
   • If read-only or locked icon appears, wait for other user to close
3. Try Compare again once files are closed

Step 5: Save Unsaved Documents First

Unsaved documents can’t be compared reliably.

1. If you want to compare an unsaved document:
   • Save it first: Ctrl+S or File > Save
   • Give it a filename
   • Choose a location
   • Click Save
2. Repeat for the second document
3. Close both documents
4. Now try Compare again with the saved versions

Step 6: Use File Path if Documents Won’t Select

Sometimes file browser doesn’t show documents.

1. In Compare dialog, instead of using folder browser
2. Right-click in the “Original document” field
3. Paste document path if you have it
4. Or type the full path: C:\Users\YourName\Documents\Document1.docx
5. Do same for “Revised document”
6. Click OK

Step 7: Try Combine Instead of Compare

Combine is sometimes more reliable.

1. Go to Review > Compare > Combine (instead of Compare)
2. Combine is designed for merging edits from multiple reviewers
3. Select documents same as Compare
4. Combine shows differences but is optimized for merging tracked changes
5. Some users find Combine works when Compare fails

Step 8: Enable More Options If Basic Compare Fails

Advanced options can help with difficult documents.

1. Open Compare dialog: Review > Compare > Compare
2. Select documents as usual
3. Before clicking OK, click “More Options” or “Show More Options” (bottom left)
4. Additional settings appear:
   • Ignore formatting: Checks only text, not formatting changes
   • Ignore spacing: Ignores space/tab differences
   • Ignore punctuation: Ignores punctuation changes
5. Uncheck options that aren’t relevant (focus on actual differences)
6. Click OK
7. Comparison might now succeed

Step 9: Compare Documents in Different Order

Sometimes order matters.

1. If Compare fails, try reversing which file is “Original” and which is “Revised”
2. Swap them and try again
3. This occasionally fixes strange errors
4. Result shows differences either way, just direction might differ

Step 10: Use Alternative Comparison Method

If Word Compare absolutely won’t work:

1. Manual side-by-side view:
   • Open both documents
   • Go to View > View Side by Side
   • Scroll through and manually note differences
2. Use Word Online comparison:
   • Upload both documents to SharePoint
   • Use SharePoint web interface > Compare versions
3. Export to Google Docs and compare:
   • Convert both to Google Docs
   • Google Docs has built-in comparison
4. Use third-party comparison tool:
   • DeltaView, Diff utilities, or similar
   • These often work when Word Compare fails

Step 11: Repair Office if Compare Persistently Fails

Compare feature might be corrupted.

1. Go to Control Panel > Programs > Programs and Features
2. Find Microsoft Office
3. Click Change
4. Select Quick Repair
5. Wait for completion (2-5 minutes)
6. If Compare still fails, repeat and select Online Repair
7. Online Repair rebuilds all Office components
8. Try Compare again

Why This Happens

1. Documents still open — Open documents interfere with Compare
2. File not saved — Unsaved documents can’t be compared
3. Incompatible format — One file is PDF, image, or non-Word format
4. File locked by another user — File in use prevents comparison
5. Corrupted document — One or both files have internal corruption
6. Compare feature bug — Older Office versions have Compare bugs
7. Path or filename issues — Special characters or very long paths break file selection
8. Insufficient disk space — Comparison creates temporary files; needs space

How to Prevent It

1. Save both documents first — Never compare unsaved files
2. Close documents before comparing — Don’t compare open files
3. Verify compatible format — Both must be .docx, .doc, or .docm
4. Use meaningful filenames — Avoid special characters in filenames
5. Keep Office updated — Updates fix Compare bugs
6. Test Compare early — Don’t wait until critical moment
7. Maintain backup copies — Keep originals before making changes
8. Use version control — For extensive revisions, use Track Changes instead of Compare

Still Not Working? Alternative Solutions

1. Side-by-side view — View > View Side by Side shows both documents at once
2. Track Changes approach — Instead of Compare, use Track Changes on one document
3. Google Docs comparison — Upload to Google Docs, use their comparison feature
4. Diff/patch tools — Command-line tools like diff (Windows/Mac) for comparing text
5. Visual comparison software — Beyond Compare, Araxis Merge, or WinDiff
6. Manual line-by-line review — Open both documents, read each line carefully
7. Reinstall Office — Complete uninstall and fresh install
8. Contact Microsoft Support — For persistent feature failures

Key Takeaways

• Close all documents before comparing (don’t compare open files)
• Save both documents first (unsaved files can’t be compared)
• Verify both are Word format (.docx, .doc), not PDF
• Use Review > Compare > Compare to select documents
• Compare creates new document with tracked changes showing all differences
• Combine is optimized for merging edits from multiple reviewers
• Use View > View Side by Side as alternative to Compare
• If Compare fails repeatedly, reinstall Office or use third-party comparison tools