diff --git a/judge/logging.py b/judge/logging.py
new file mode 100644
index 0000000..8d9f154
--- /dev/null
+++ b/judge/logging.py
@@ -0,0 +1,7 @@
+import logging
+
+error_log = logging.getLogger("judge.errors")
+
+
+def log_exception(msg):
+    error_log.exception(msg)
diff --git a/judge/models/problem.py b/judge/models/problem.py
index 9560be8..98e477b 100644
--- a/judge/models/problem.py
+++ b/judge/models/problem.py
@@ -556,7 +556,7 @@ class Problem(models.Model, PageVotable, Bookmarkable):
 
     def save(self, *args, **kwargs):
         super(Problem, self).save(*args, **kwargs)
-        if self.code != self.__original_code:
+        if self.__original_code and self.code != self.__original_code:
             if hasattr(self, "data_files") or self.pdf_description:
                 try:
                     problem_data_storage.rename(self.__original_code, self.code)
diff --git a/judge/models/problem_data.py b/judge/models/problem_data.py
index d61b528..b04d2ab 100644
--- a/judge/models/problem_data.py
+++ b/judge/models/problem_data.py
@@ -162,10 +162,10 @@ class ProblemData(models.Model):
                         get_file_cachekey(file),
                     )
                     cache.delete(cache_key)
-            except BadZipFile:
+            except (BadZipFile, FileNotFoundError):
                 pass
-        if self.zipfile != self.__original_zipfile and self.__original_zipfile:
-            self.__original_zipfile.delete(save=False)
+            if self.zipfile != self.__original_zipfile:
+                self.__original_zipfile.delete(save=False)
         return super(ProblemData, self).save(*args, **kwargs)
 
     def has_yml(self):
diff --git a/judge/utils/problem_data.py b/judge/utils/problem_data.py
index 954c213..023c0be 100644
--- a/judge/utils/problem_data.py
+++ b/judge/utils/problem_data.py
@@ -12,6 +12,8 @@ from django.urls import reverse
 from django.utils.translation import gettext as _
 from django.core.cache import cache
 
+from judge.logging import log_exception
+
 if os.altsep:
 
     def split_path_first(
@@ -323,11 +325,13 @@ def get_problem_case(problem, files):
         settings.DMOJ_PROBLEM_DATA_ROOT, str(problem.data_files.zipfile)
     )
     if not os.path.exists(archive_path):
-        raise Exception('archive file "%s" does not exist' % archive_path)
+        log_exception('archive file "%s" does not exist' % archive_path)
+        return {}
     try:
         archive = zipfile.ZipFile(archive_path, "r")
     except zipfile.BadZipfile:
-        raise Exception('bad archive: "%s"' % archive_path)
+        log_exception('bad archive: "%s"' % archive_path)
+        return {}
 
     for file in uncached_files:
         cache_key = "problem_archive:%s:%s" % (problem.code, get_file_cachekey(file))
diff --git a/judge/views/problem_data.py b/judge/views/problem_data.py
index 121d570..0525395 100644
--- a/judge/views/problem_data.py
+++ b/judge/views/problem_data.py
@@ -56,6 +56,7 @@ from judge.utils.fine_uploader import (
     FineUploadForm,
 )
 from judge.views.problem import ProblemMixin
+from judge.logging import log_exception
 
 mimetypes.init()
 mimetypes.add_type("application/x-yaml", ".yml")
@@ -249,6 +250,9 @@ class ProblemDataView(TitleMixin, ProblemManagerMixin):
                 return ZipFile(data.zipfile.path).namelist()
         except BadZipfile:
             return []
+        except FileNotFoundError as e:
+            log_exception(e)
+            return []
         return []
 
     def get_context_data(self, **kwargs):
diff --git a/judge/views/submission.py b/judge/views/submission.py
index 61982cf..26300b0 100644
--- a/judge/views/submission.py
+++ b/judge/views/submission.py
@@ -195,8 +195,8 @@ def get_cases_data(submission):
             continue
         count += 1
         problem_data[count] = {
-            "input": case_data[case.input_file] if case.input_file else "",
-            "answer": case_data[case.output_file] if case.output_file else "",
+            "input": case_data.get(case.input_file, "") if case.input_file else "",
+            "answer": case_data.get(case.output_file, "") if case.output_file else "",
         }
 
     return problem_data