diff --git a/runtime/src/bank/partitioned_epoch_rewards/distribution.rs b/runtime/src/bank/partitioned_epoch_rewards/distribution.rs
index c627da706b1a38..10653cce6a9d55 100644
--- a/runtime/src/bank/partitioned_epoch_rewards/distribution.rs
+++ b/runtime/src/bank/partitioned_epoch_rewards/distribution.rs
@@ -150,7 +150,10 @@ impl Bank {
         let (mut account, stake_state): (AccountSharedData, StakeStateV2) = stake_account.into();
         let StakeStateV2::Stake(meta, stake, flags) = stake_state else {
             // StakesCache only stores accounts where StakeStateV2::delegation().is_some()
-            unreachable!()
+            unreachable!(
+                "StakesCache entry {:?} failed StakeStateV2 deserialization",
+                partitioned_stake_reward.stake_pubkey
+            )
         };
         account
             .checked_add_lamports(partitioned_stake_reward.stake_reward_info.lamports as u64)