diff --git a/svn_mirror/git_to_svn.py b/svn_mirror/git_to_svn.py
index 19f3ce3..f99c1e2 100644
--- a/svn_mirror/git_to_svn.py
+++ b/svn_mirror/git_to_svn.py
@@ -129,15 +129,60 @@ def _ensure_wc(mirror: Mirror, svn_branch: str):
     if not (wc / ".svn").exists():
         logger.info("Checking out SVN WC for %s …", svn_branch)
         wc.mkdir(parents=True, exist_ok=True)
-        _run_svn(["checkout", "--ignore-externals", svn_url, str(wc)],
-                 timeout=300, auth_args=auth_args)
+        try:
+            _run_svn(["checkout", "--ignore-externals", svn_url, str(wc)],
+                     timeout=900, auth_args=auth_args)
+        except GitToSVNError:
+            _cleanup_failed_wc(wc)
+            raise
     else:
-        logger.debug("Updating SVN WC for %s …", svn_branch)
-        _run_svn(["revert", "-R", "."], timeout=120, wc=wc, auth_args=auth_args)
-        _run_svn(["update", "--ignore-externals"], timeout=120, wc=wc, auth_args=auth_args)
+        _try_revert(wc, auth_args)
+        try:
+            _run_svn(["update", "--ignore-externals"], timeout=120,
+                     wc=wc, auth_args=auth_args)
+        except GitToSVNError as e:
+            if _is_lock_error(e):
+                logger.warning("WC locked – running cleanup for %s", svn_branch)
+                _run_svn(["cleanup"], timeout=120, wc=wc, auth_args=auth_args)
+                _try_revert(wc, auth_args)
+                _run_svn(["update", "--ignore-externals"], timeout=120,
+                         wc=wc, auth_args=auth_args)
+            else:
+                raise
     return wc
 
 
+def _is_lock_error(e: GitToSVNError) -> bool:
+    return "E155004" in str(e) or "locked" in str(e).lower()
+
+
+def _try_revert(wc: Path, auth_args: Optional[list]):
+    try:
+        _run_svn(["revert", "-R", "."], timeout=120, wc=wc, auth_args=auth_args)
+    except GitToSVNError as e:
+        if _is_lock_error(e):
+            logger.warning("WC locked during revert – running cleanup")
+            _run_svn(["cleanup"], timeout=120, wc=wc, auth_args=auth_args)
+            _run_svn(["revert", "-R", "."], timeout=120,
+                     wc=wc, auth_args=auth_args)
+        else:
+            raise
+
+
+def _cleanup_failed_wc(wc: Path):
+    """Remove a partial/failed SVN working copy."""
+    import shutil
+    import time
+    for attempt in range(3):
+        try:
+            if wc.exists():
+                shutil.rmtree(wc)
+            return
+        except PermissionError:
+            time.sleep(1)
+    logger.warning("Could not fully remove failed WC at %s", wc)
+
+
 # ─── Author mapping (reverse) ──────────────────────────────────