diff --git a/svn_mirror/git_to_svn.py b/svn_mirror/git_to_svn.py
index 5ad283b..060a160 100644
--- a/svn_mirror/git_to_svn.py
+++ b/svn_mirror/git_to_svn.py
@@ -133,9 +133,15 @@ def _ensure_wc(mirror: Mirror, svn_branch: str):
         try:
             _run_svn(["checkout", "--ignore-externals", svn_url, str(wc)],
                      timeout=900, auth_args=auth_args)
-        except GitToSVNError:
+        except GitToSVNError as e:
             _cleanup_failed_wc(wc)
-            raise
+            if _is_svn_not_found(e):
+                _create_svn_branch(mirror, svn_branch, auth_args)
+                wc.mkdir(parents=True, exist_ok=True)
+                _run_svn(["checkout", "--ignore-externals", svn_url, str(wc)],
+                         timeout=900, auth_args=auth_args)
+            else:
+                raise
     else:
         _try_revert(wc, auth_args)
         try:
@@ -189,6 +195,40 @@ def _cleanup_failed_wc(wc: Path):
     logger.warning("Could not fully remove failed WC at %s", wc)
 
 
+def _is_svn_not_found(e: GitToSVNError) -> bool:
+    return "E170000" in str(e)
+
+
+def _create_svn_branch(mirror: Mirror, svn_branch: str,
+                       auth_args: Optional[list]):
+    """Create an SVN branch by copying from trunk.
+
+    Called when a Git branch has no corresponding SVN path yet.
+    """
+    root = mirror.config.svn.url.rstrip("/")
+    trunk_url = f"{root}/{mirror.config.svn.trunk}"
+    branch_url = f"{root}/{svn_branch}"
+    branch_name = svn_branch.rsplit("/", 1)[-1]
+    msg = f"Create branch {branch_name} from {mirror.config.svn.trunk}"
+    logger.info("Creating SVN branch: %s …", branch_url)
+    result = _run_svn(
+        ["copy", trunk_url, branch_url, "-m", msg],
+        timeout=120, auth_args=auth_args,
+    )
+    new_rev = _parse_commit_revision(result)
+    # Restore author revprop (svn copy uses buildbot as committer)
+    try:
+        _run_svn(
+            ["propset", "--revprop", "-r", str(new_rev),
+             "svn:author", mirror.config.svn.username or "buildbot",
+             root],
+            timeout=30, auth_args=auth_args,
+        )
+    except GitToSVNError:
+        logger.debug("Could not set svn:author for branch creation r%d", new_rev)
+    logger.info("Created SVN branch %s (r%d)", branch_url, new_rev)
+
+
 # ─── Author mapping (reverse) ──────────────────────────────────