diff --git a/libavcodec/h264_picture.c b/libavcodec/h264_picture.c
index 66fd9bc4cb..adf8a32378 100644
--- a/libavcodec/h264_picture.c
+++ b/libavcodec/h264_picture.c
@@ -252,9 +252,11 @@ int ff_h264_field_end(H264Context *h, H264SliceContext *sl, int in_setup)
                    "hardware accelerator failed to decode picture\n");
     } else if (!in_setup && cur->needs_fg && (!FIELD_PICTURE(h) || !h->first_field)) {
         AVFrameSideData *sd = av_frame_get_side_data(cur->f, AV_FRAME_DATA_FILM_GRAIN_PARAMS);
-        av_assert0(sd); // always present if `cur->needs_fg`
-        err = ff_h274_apply_film_grain(cur->f_grain, cur->f, &h->h274db,
-                                       (AVFilmGrainParams *) sd->data);
+
+        err = AVERROR_INVALIDDATA;
+        if (sd) // a decoding error may have happened before the side data could be allocated
+            err = ff_h274_apply_film_grain(cur->f_grain, cur->f, &h->h274db,
+                                           (AVFilmGrainParams *) sd->data);
         if (err < 0) {
             av_log(h->avctx, AV_LOG_WARNING, "Failed synthesizing film "
                    "grain, ignoring: %s\n", av_err2str(err));