diff --git a/internal/diagnostics/repo.go b/internal/diagnostics/repo.go
index 9797aafa..1f2b2aa0 100644
--- a/internal/diagnostics/repo.go
+++ b/internal/diagnostics/repo.go
@@ -69,6 +69,12 @@ func (r *PostgresRepository) InsertReceiving(ctx context.Context, input InsertRe
 	}
 
 	crashSummary := truncateCrashSummary(input.CrashSummary)
+	sessionIDs := input.PlaybackSessionIDs
+	if sessionIDs == nil {
+		// pgx binds a nil slice as SQL NULL, which bypasses the column's
+		// '{}' default and violates its NOT NULL constraint.
+		sessionIDs = []string{}
+	}
 	for attempt := 0; attempt < retries; attempt++ {
 		id := reportIDGenerator()
 		if _, err := uuid.Parse(id); err != nil {
@@ -95,7 +101,7 @@ func (r *PostgresRepository) InsertReceiving(ctx context.Context, input InsertRe
 		`, id, shortID, input.UserID, nullableString(input.ProfileID), input.CapturedAt,
 			strings.TrimSpace(input.ReportType), strings.TrimSpace(input.Platform),
 			strings.TrimSpace(input.AppVersion), nullableString(crashSummary),
-			string(input.Manifest), input.PlaybackSessionIDs).Scan(&insertedID, &insertedShortID)
+			string(input.Manifest), sessionIDs).Scan(&insertedID, &insertedShortID)
 		if errors.Is(err, pgx.ErrNoRows) {
 			continue
 		}
diff --git a/internal/diagnostics/service.go b/internal/diagnostics/service.go
index 2121d490..1f9ba254 100644
--- a/internal/diagnostics/service.go
+++ b/internal/diagnostics/service.go
@@ -172,6 +172,12 @@ func (s *Service) Ingest(ctx context.Context, userID int, profileID *string, man
 		reason := "insert_failed"
 		if errors.Is(err, ErrQuotaExceeded) {
 			reason = "quota_exceeded"
+		} else {
+			s.logger.ErrorContext(ctx, "diagnostic report insert failed",
+				"component", "diagnostics",
+				"user_id", userID,
+				"error", err,
+			)
 		}
 		s.logRejected(ctx, "", userID, manifest.Report.Platform, manifest.Report.Type, manifest.Archive.Bytes, reason)
 		return IngestResult{}, err
@@ -182,6 +188,12 @@ func (s *Service) Ingest(ctx context.Context, userID int, profileID *string, man
 	if err != nil {
 		s.compensateFailedUpload(ctx, reserved.ID, key)
 		rejectErr := classifyBundleUploadError(err)
+		s.logger.ErrorContext(ctx, "diagnostic bundle validation failed",
+			"component", "diagnostics",
+			"report_id", reserved.ID,
+			"user_id", userID,
+			"error", err,
+		)
 		s.logRejected(ctx, reserved.ID, userID, manifest.Report.Platform, manifest.Report.Type, manifest.Archive.Bytes, rejectReason(rejectErr))
 		return IngestResult{}, rejectErr
 	}