diff --git a/CTFd/api/v1/challenges.py b/CTFd/api/v1/challenges.py
index bbdc57b..9868476 100644
--- a/CTFd/api/v1/challenges.py
+++ b/CTFd/api/v1/challenges.py
@@ -378,7 +378,7 @@ class ChallengeAttempt(Resource):
             log(
                 "submissions",
                 "[{date}] {name} submitted {submission} on {challenge_id} with kpm {kpm} [TOO FAST]",
-                submission=request_data["submission"].encode("utf-8"),
+                submission=request_data.get("submission", "").encode("utf-8"),
                 challenge_id=challenge_id,
                 kpm=kpm,
             )
@@ -425,7 +425,7 @@ class ChallengeAttempt(Resource):
                 log(
                     "submissions",
                     "[{date}] {name} submitted {submission} on {challenge_id} with kpm {kpm} [CORRECT]",
-                    submission=request_data["submission"].encode("utf-8"),
+                    submission=request_data.get("submission", "").encode("utf-8"),
                     challenge_id=challenge_id,
                     kpm=kpm,
                 )
@@ -443,7 +443,7 @@ class ChallengeAttempt(Resource):
                 log(
                     "submissions",
                     "[{date}] {name} submitted {submission} on {challenge_id} with kpm {kpm} [WRONG]",
-                    submission=request_data["submission"].encode("utf-8"),
+                    submission=request_data.get("submission", "").encode("utf-8"),
                     challenge_id=challenge_id,
                     kpm=kpm,
                 )
@@ -477,7 +477,7 @@ class ChallengeAttempt(Resource):
             log(
                 "submissions",
                 "[{date}] {name} submitted {submission} on {challenge_id} with kpm {kpm} [ALREADY SOLVED]",
-                submission=request_data["submission"].encode("utf-8"),
+                submission=request_data.get("submission", "").encode("utf-8"),
                 challenge_id=challenge_id,
                 kpm=kpm,
             )