diff --git a/cmd/ztest.c b/cmd/ztest.c
index 3b63ad43f..89264c97f 100644
--- a/cmd/ztest.c
+++ b/cmd/ztest.c
@@ -1816,7 +1816,7 @@ ztest_zd_fini(ztest_ds_t *zd)
 	(ztest_random(10) == 0 ? DMU_TX_NOWAIT : DMU_TX_WAIT)
 
 static uint64_t
-ztest_tx_assign(dmu_tx_t *tx, uint64_t txg_how, const char *tag)
+ztest_tx_assign(dmu_tx_t *tx, dmu_tx_flag_t txg_how, const char *tag)
 {
 	uint64_t txg;
 	int error;
@@ -1829,9 +1829,10 @@ ztest_tx_assign(dmu_tx_t *tx, uint64_t txg_how, const char *tag)
 		if (error == ERESTART) {
 			ASSERT3U(txg_how, ==, DMU_TX_NOWAIT);
 			dmu_tx_wait(tx);
-		} else {
-			ASSERT3U(error, ==, ENOSPC);
+		} else if (error == ENOSPC) {
 			ztest_record_enospc(tag);
+		} else {
+			ASSERT(error == EDQUOT || error == EIO);
 		}
 		dmu_tx_abort(tx);
 		return (0);
diff --git a/module/zfs/dmu_tx.c b/module/zfs/dmu_tx.c
index b5e9c7e6e..d85d8b894 100644
--- a/module/zfs/dmu_tx.c
+++ b/module/zfs/dmu_tx.c
@@ -1054,7 +1054,7 @@ dmu_tx_try_assign(dmu_tx_t *tx)
 
 	if (tx->tx_err) {
 		DMU_TX_STAT_BUMP(dmu_tx_error);
-		return (tx->tx_err);
+		return (SET_ERROR(EIO));
 	}
 
 	if (spa_suspended(spa)) {
@@ -1190,7 +1190,8 @@ dmu_tx_unassign(dmu_tx_t *tx)
  * If DMU_TX_WAIT is set and the currently open txg is full, this function
  * will wait until there's a new txg. This should be used when no locks
  * are being held. With this bit set, this function will only fail if
- * we're truly out of space (or over quota).
+ * we're truly out of space (ENOSPC), over quota (EDQUOT), or required
+ * data for the transaction could not be read from disk (EIO).
  *
  * If DMU_TX_WAIT is *not* set and we can't assign into the currently open
  * txg without blocking, this function will return immediately with
@@ -1279,8 +1280,11 @@ dmu_tx_assign(dmu_tx_t *tx, dmu_tx_flag_t flags)
 		 * Return unless we decided to retry, or the caller does not
 		 * want to block.
 		 */
-		if (err != ERESTART || !(flags & DMU_TX_WAIT))
+		if (err != ERESTART || !(flags & DMU_TX_WAIT)) {
+			ASSERT(err == EDQUOT || err == ENOSPC ||
+			    err == ERESTART || err == EIO);
 			return (err);
+		}
 
 		/*
 		 * Wait until there's room in this txg, or until it's been
diff --git a/module/zfs/dsl_dir.c b/module/zfs/dsl_dir.c
index 8c59fbf60..f24cd2049 100644
--- a/module/zfs/dsl_dir.c
+++ b/module/zfs/dsl_dir.c
@@ -1450,6 +1450,8 @@ dsl_dir_tempreserve_space(dsl_dir_t *dd, uint64_t lsize, uint64_t asize,
 			    MSEC2NSEC(10), MSEC2NSEC(10));
 			err = SET_ERROR(ERESTART);
 		}
+
+		ASSERT3U(err, ==, ERESTART);
 	}
 
 	if (err == 0) {