Update WebDAV troubleshooting guide with URL encoding fix

- Add section on URL encoding issues causing HTTP 400 errors
- Document nginx proxy_pass solution for preserving request URI
- Update final working configuration with HTTP/1.1 fixes
- Include Connection header and proxy_http_version settings

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/troubleshooting/webdav-copyparty.md

@@ -39,6 +39,27 @@ server {
 - Error: `HTTP/1.1 403 Forbidden`
 
 **Solution**: Add `d` (delete) permission to user accounts:
+
+### 3. URL Encoding Issues
+**Problem**: Files/folders with spaces or special characters in names caused HTTP 400 errors.
+
+**Symptoms**:
+- Files without spaces upload successfully
+- Files with spaces in path fail: `HTTP/1.1 400 Bad Request`
+- Logs show "bad headers" errors from copyparty
+- URLs like `/files/folder/file%20name.txt` fail
+
+**Solution**: Pass original request URI to preserve URL encoding:
+```nginx
+location ~ ^/files(/.*)?$ {
+    # Pass original request URI to preserve URL encoding
+    proxy_pass http://127.0.0.1:8082;
+    # ... other proxy settings
+}
+```
+
+Instead of `proxy_pass http://127.0.0.1:8082/files$1;` which manipulates the path.
+
 ```ini
 [/shared]
   /home/hoborg/shared
@@ -115,7 +136,8 @@ server {
         # Explicitly allow WebDAV methods
         limit_except GET POST PUT DELETE PROPFIND PROPPATCH MKCOL COPY MOVE LOCK UNLOCK { deny all; }
 
-        proxy_pass http://127.0.0.1:8082/files$1;
+        # Pass original request URI to preserve URL encoding
+        proxy_pass http://127.0.0.1:8082;
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
@@ -140,6 +162,10 @@ server {
         # Critical: Streaming uploads for WebDAV
         proxy_buffering off;
         proxy_request_buffering off;
+        
+        # Critical: Use HTTP/1.1 and fix connection headers
+        proxy_http_version 1.1;
+        proxy_set_header Connection "";
 
         # Critical: Disable nginx response modifications
         proxy_redirect off;