diff --git a/access/views.py b/access/views.py
index a47f7fc..f306d6a 100644
--- a/access/views.py
+++ b/access/views.py
@@ -191,6 +191,7 @@ def aplus_json(request: HttpRequest, course_key: str) -> HttpResponse:
         except ConfigError as e:
             errors.append(f"Failed to load newly built course due to this error: {e}")
             errors.append("Attempting to load previous version of the course...")
+            logger.warn(f"Failed to load newly built course due to this error: {e}")
         else:
             defaults_path = CourseConfig.defaults_path(course_key, source=ConfigSource.STORE)
 
@@ -198,6 +199,7 @@ def aplus_json(request: HttpRequest, course_key: str) -> HttpResponse:
         try:
             config = CourseConfig.get(course_key, source=ConfigSource.PUBLISH)
         except ConfigError as e:
+            logger.error(f"aplus_json: failed to get config for {course_key}")
             try:
                 Course.objects.get(key=course_key)
             except:
diff --git a/builder/builder.py b/builder/builder.py
index 7e34d9e..534c661 100644
--- a/builder/builder.py
+++ b/builder/builder.py
@@ -28,7 +28,7 @@
 from access.config import INDEX, ConfigSource, CourseConfig, load_meta, META
 from access.parser import ConfigError
 from builder.configure import configure_graders, publish_graders
-from util.files import is_subpath, renames, rm_path, FileLock
+from util.files import is_subpath, renames, rm_path, rm_paths, FileLock
 from util.git import checkout, clone_if_doesnt_exist, get_commit_hash, get_commit_metadata
 from util.pydantic import validation_error_str, validation_warning_str
 from util.static import static_url, static_url_path, symbolic_link
@@ -336,14 +336,16 @@ def publish(course_key: str) -> List[str]:
 
     config = None
     errors = []
+    tmpfiles = []
     if Path(store_path).exists():
         with FileLock(store_path):
             try:
                 config = CourseConfig.get(course_key, source=ConfigSource.STORE)
             except ConfigError as e:
                 errors.append(f"Failed to load newly built course for this reason: {e}")
+                logger.warn(f"Failed to load newly built course for this reason: {e}")
             else:
-                renames([
+                tmpfiles = renames([
                     (store_path, prod_path),
                     (store_defaults_path, prod_defaults_path),
                     (store_version_path, prod_version_path),
@@ -356,6 +358,7 @@ def publish(course_key: str) -> List[str]:
                 config = CourseConfig.get(course_key, source=ConfigSource.PUBLISH)
             except ConfigError as e:
                 errors.append(f"Failed to load already published config: {e}")
+                logger.error(f"Failed to load already published config: {e}")
 
     if config is None:
         if errors:
@@ -364,8 +367,13 @@ def publish(course_key: str) -> List[str]:
             raise Exception(f"Course directory not found for {course_key} - the course probably has not been built")
 
     symbolic_link(config)
+    errors = errors + publish_graders(config)
 
-    return errors + publish_graders(config)
+    # Remove temporary files that were created during renaming.
+    # This may block the execution for a while on courses with many files.
+    rm_paths(tmpfiles)
+
+    return errors
 
 
 # the task locks can get stuck if the program suddenly shuts down,
diff --git a/util/files.py b/util/files.py
index d52e1ff..b3cdfcb 100644
--- a/util/files.py
+++ b/util/files.py
@@ -9,7 +9,7 @@
 import tempfile
 import time
 from types import TracebackType
-from typing import Dict, Generator, Iterable, Optional, Tuple, Type, Union
+from typing import Dict, Generator, Iterable, Optional, Tuple, Type, Union, List
 
 from django.conf import settings
 from django.http.response import FileResponse as DjangoFileResponse, HttpResponse
@@ -46,6 +46,12 @@ def rm_path(path: Union[str, Path]) -> None:
         path.unlink()
 
 
+def rm_paths(paths: Iterable[Union[str, Path]]) -> None:
+    for path in paths:
+        if path is not None:
+            rm_path(path)
+
+
 def is_subpath(child: PathLike, parent: Optional[PathLike] = None) -> bool:
     """
     If parent is not None, returns whether child is a subpath of (contained in)
@@ -168,9 +174,10 @@ def rename(src: PathLike, dst: PathLike, keep_tmp=False) -> Optional[str]:
     return tmpdst
 
 
-def renames(pairs: Iterable[Tuple[PathLike, PathLike]]) -> None:
+def renames(pairs: Iterable[Tuple[PathLike, PathLike]]) -> List[str]:
     """
     Renames multiple files and directories while making sure that either all or none succeed.
+    Returns a list of generated tmp directories (for later removal).
     """
     done = set()
     try:
@@ -183,10 +190,8 @@ def renames(pairs: Iterable[Tuple[PathLike, PathLike]]) -> None:
             if os.path.exists(tmp):
                 rename(tmp, dst)
         raise
-    else:
-        for _, _, tmp in done:
-            if tmp is not None:
-                rm_path(tmp)
+
+    return list(map(lambda x: x[2], done))
 
 
 def _try_lockf(lockfile, flags) -> Optional[OSError]: