diff --git a/block.c b/block.c
index a2542c9..cccae5a 100644
--- a/block.c
+++ b/block.c
@@ -363,6 +363,7 @@
 
 void bdrv_register(BlockDriver *bdrv)
 {
+    assert(bdrv->format_name);
     QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
 }
 
@@ -2759,10 +2760,10 @@
 
     if (bs->backing) {
         bdrv_unref_child(bs, bs->backing);
+        bs->backing = NULL;
     }
 
     if (!backing_hd) {
-        bs->backing = NULL;
         goto out;
     }
 
diff --git a/block/qcow2.c b/block/qcow2.c
index d44b456..d1da3d9 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1758,6 +1758,7 @@
     g_free(s->image_data_file);
     if (has_data_file(bs)) {
         bdrv_unref_child(bs, s->data_file);
+        s->data_file = NULL;
     }
     g_free(s->unknown_header_fields);
     cleanup_unknown_header_ext(bs);
@@ -2621,6 +2622,7 @@
 
     if (has_data_file(bs)) {
         bdrv_unref_child(bs, s->data_file);
+        s->data_file = NULL;
     }
 
     qcow2_refcount_close(bs);
@@ -4811,6 +4813,7 @@
         if (local_err) {
             error_propagate(errp, local_err);
             qapi_free_ImageInfoSpecific(spec_info);
+            qapi_free_QCryptoBlockInfo(encrypt_info);
             return NULL;
         }
         *spec_info->u.qcow2.data = (ImageInfoSpecificQCow2){
diff --git a/tests/qemu-iotests/026 b/tests/qemu-iotests/026
index b05a469..b9713eb 100755
--- a/tests/qemu-iotests/026
+++ b/tests/qemu-iotests/026
@@ -240,37 +240,6 @@
 
 _check_test_img
 
-echo
-echo === Avoid freeing external data clusters on failure ===
-echo
-
-# Similar test as the last one, except we test what happens when there
-# is an error when writing to an external data file instead of when
-# writing to a preallocated zero cluster
-_make_test_img -o "data_file=$TEST_IMG.data_file" $CLUSTER_SIZE
-
-# Put blkdebug above the data-file, and a raw node on top of that so
-# that blkdebug will see a write_aio event and emit an error
-$QEMU_IO -c "write 0 $CLUSTER_SIZE" \
-    "json:{
-         'driver': 'qcow2',
-         'file': { 'driver': 'file', 'filename': '$TEST_IMG' },
-         'data-file': {
-             'driver': 'raw',
-             'file': {
-                 'driver': 'blkdebug',
-                 'config': '$TEST_DIR/blkdebug.conf',
-                 'image': {
-                     'driver': 'file',
-                     'filename': '$TEST_IMG.data_file'
-                 }
-             }
-         }
-     }" \
-    | _filter_qemu_io
-
-_check_test_img
-
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/026.out b/tests/qemu-iotests/026.out
index c1b3b58..8398999 100644
--- a/tests/qemu-iotests/026.out
+++ b/tests/qemu-iotests/026.out
@@ -653,10 +653,4 @@
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 write failed: Input/output error
 No errors were found on the image.
-
-=== Avoid freeing external data clusters on failure ===
-
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1024 data_file=TEST_DIR/t.IMGFMT.data_file
-write failed: Input/output error
-No errors were found on the image.
 *** done
diff --git a/tests/qemu-iotests/026.out.nocache b/tests/qemu-iotests/026.out.nocache
index 8d50016..9359d26 100644
--- a/tests/qemu-iotests/026.out.nocache
+++ b/tests/qemu-iotests/026.out.nocache
@@ -661,10 +661,4 @@
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 write failed: Input/output error
 No errors were found on the image.
-
-=== Avoid freeing external data clusters on failure ===
-
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1024 data_file=TEST_DIR/t.IMGFMT.data_file
-write failed: Input/output error
-No errors were found on the image.
 *** done
diff --git a/tests/qemu-iotests/085 b/tests/qemu-iotests/085
index 46981db..dd3c993 100755
--- a/tests/qemu-iotests/085
+++ b/tests/qemu-iotests/085
@@ -39,6 +39,7 @@
 _cleanup()
 {
     _cleanup_qemu
+    _cleanup_test_img
     for i in $(seq 1 ${SNAPSHOTS})
     do
         _rm_test_img "${TEST_DIR}/${i}-${snapshot_virt0}"
diff --git a/tests/qemu-iotests/087 b/tests/qemu-iotests/087
index d6c8613..bdfdad3 100755
--- a/tests/qemu-iotests/087
+++ b/tests/qemu-iotests/087
@@ -26,6 +26,12 @@
 
 status=1	# failure is the default!
 
+_cleanup()
+{
+    _cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
 # get standard environment, filters and checks
 . ./common.rc
 . ./common.filter
diff --git a/tests/qemu-iotests/279 b/tests/qemu-iotests/279
index 30d29b1..75a4747 100755
--- a/tests/qemu-iotests/279
+++ b/tests/qemu-iotests/279
@@ -26,7 +26,7 @@
 _cleanup()
 {
     _cleanup_test_img
-    rm -f "$TEST_IMG.mid"
+    _rm_test_img "$TEST_IMG.mid"
 }
 trap "_cleanup; exit \$status" 0 1 2 3 15
 
diff --git a/tests/qemu-iotests/289 b/tests/qemu-iotests/289
new file mode 100755
index 0000000..1c11d40
--- /dev/null
+++ b/tests/qemu-iotests/289
@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+#
+# qcow2 v3-exclusive error path testing
+# (026 tests paths common to v2 and v3)
+#
+# Copyright (C) 2020 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+seq=$(basename $0)
+echo "QA output created by $seq"
+
+status=1	# failure is the default!
+
+_cleanup()
+{
+    _cleanup_test_img
+    rm "$TEST_DIR/blkdebug.conf"
+    rm -f "$TEST_IMG.data_file"
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+. ./common.pattern
+
+_supported_fmt qcow2
+_supported_proto file
+# This is a v3-exclusive test;
+# As for data_file, error paths often very much depend on whether
+# there is an external data file or not; so we create one exactly when
+# we want to test it
+_unsupported_imgopts 'compat=0.10' data_file
+
+echo
+echo === Avoid freeing external data clusters on failure ===
+echo
+
+cat > "$TEST_DIR/blkdebug.conf" <<EOF
+[inject-error]
+event = "write_aio"
+errno = "5"
+once = "on"
+EOF
+
+# Test what happens when there is an error when writing to an external
+# data file instead of when writing to a preallocated zero cluster
+_make_test_img -o "data_file=$TEST_IMG.data_file" 64k
+
+# Put blkdebug above the data-file, and a raw node on top of that so
+# that blkdebug will see a write_aio event and emit an error.  This
+# will then trigger the alloc abort code, which we want to test here.
+$QEMU_IO -c "write 0 64k" \
+    "json:{
+         'driver': 'qcow2',
+         'file': { 'driver': 'file', 'filename': '$TEST_IMG' },
+         'data-file': {
+             'driver': 'raw',
+             'file': {
+                 'driver': 'blkdebug',
+                 'config': '$TEST_DIR/blkdebug.conf',
+                 'image': {
+                     'driver': 'file',
+                     'filename': '$TEST_IMG.data_file'
+                 }
+             }
+         }
+     }" \
+    | _filter_qemu_io
+
+_check_test_img
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/289.out b/tests/qemu-iotests/289.out
new file mode 100644
index 0000000..e54e262
--- /dev/null
+++ b/tests/qemu-iotests/289.out
@@ -0,0 +1,8 @@
+QA output created by 289
+
+=== Avoid freeing external data clusters on failure ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=65536 data_file=TEST_DIR/t.IMGFMT.data_file
+write failed: Input/output error
+No errors were found on the image.
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index ec2b230..79c6dfc 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -295,3 +295,4 @@
 284 rw
 286 rw quick
 288 quick
+289 rw quick