diff --git a/accounts/abi/bind/backends/simulated.go b/accounts/abi/bind/backends/simulated.go
index 852be1ed3a..70c6e56c6f 100644
--- a/accounts/abi/bind/backends/simulated.go
+++ b/accounts/abi/bind/backends/simulated.go
@@ -412,9 +412,9 @@ func (b *SimulatedBackend) EstimateGas(ctx context.Context, call ethereum.CallMs
 
 		if err != nil {
 			if err == core.ErrInsufficientIntrinsicGas {
-				return true, nil, nil
+				return true, nil, nil // Special case, raise gas limit
 			}
-			return true, nil, err
+			return true, nil, err // Bail out
 		}
 		return res.Failed(), res, nil
 	}
@@ -442,9 +442,17 @@ func (b *SimulatedBackend) EstimateGas(ctx context.Context, call ethereum.CallMs
 			return 0, err
 		}
 		if failed {
-			if result != nil && len(result.RevertReason) != 0 {
-				return 0, fmt.Errorf("Reverted %x", result.RevertReason)
+			if result != nil {
+				// If the revert reason is provided, return it to user.
+				if result.Err == vm.ErrExecutionReverted {
+					return 0, fmt.Errorf("transaction reverted (0x%x)", result.RevertReason)
+				}
+				// If it's an invalid transaction, return the concrete vm error
+				if result.Err != vm.ErrOutOfGas {
+					return 0, fmt.Errorf("always failing transaction (%v)", result.Err)
+				}
 			}
+			// Otherwise, the specified gas cap is too low
 			return 0, fmt.Errorf("gas required exceeds allowance (%d)", cap)
 		}
 	}
diff --git a/core/error.go b/core/error.go
index 587887bba3..8e0716e6c1 100644
--- a/core/error.go
+++ b/core/error.go
@@ -29,8 +29,8 @@ var (
 	ErrNoGenesis = errors.New("genesis not found in chain")
 )
 
-// State transition consensus errors, any of them
-// encountered can lead to consensus issue.
+// State transition consensus errors, any of them encountered during
+// the block processing can lead to consensus issue.
 var (
 	// ErrNonceTooLow is returned if the nonce of a transaction is lower than the
 	// one present in the local chain.
@@ -59,11 +59,3 @@ var (
 	// is not enought to cover intrinsic gas usage.
 	ErrInsufficientIntrinsicGas = errors.New("insufficient intrinsic gas")
 )
-
-type ConsensusError struct {
-	Reason error
-}
-
-func (ce *ConsensusError) Unwarp() error {
-	return ce.Reason
-}
diff --git a/core/state_transition.go b/core/state_transition.go
index 19ddd44b75..5afbfc4c1e 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -219,7 +219,7 @@ func (st *StateTransition) TransitionDb() (*ExecutionResult, error) {
 	istanbul := st.evm.ChainConfig().IsIstanbul(st.evm.BlockNumber)
 	contractCreation := msg.To() == nil
 
-	// Check clauses 4-5, subtract intrinsic if everything is correct
+	// Check clauses 4-5, subtract intrinsic gas if everything is correct
 	gas, err := IntrinsicGas(st.data, contractCreation, homestead, istanbul)
 	if err != nil {
 		return nil, err
@@ -229,7 +229,7 @@ func (st *StateTransition) TransitionDb() (*ExecutionResult, error) {
 	}
 	st.gas -= gas
 
-	// Check clauses 6
+	// Check clause 6
 	if msg.Value().Sign() > 0 && !st.evm.CanTransfer(st.state, msg.From(), msg.Value()) {
 		return nil, ErrInsufficientBalanceForTransfer
 	}
diff --git a/graphql/graphql.go b/graphql/graphql.go
index 34e7f82efc..159c6845f3 100644
--- a/graphql/graphql.go
+++ b/graphql/graphql.go
@@ -815,7 +815,7 @@ func (b *Block) Call(ctx context.Context, args struct {
 		data:    result.Result,
 		gasUsed: hexutil.Uint64(result.UsedGas),
 		status:  status,
-	}, err
+	}, nil
 }
 
 func (b *Block) EstimateGas(ctx context.Context, args struct {
@@ -884,7 +884,7 @@ func (p *Pending) Call(ctx context.Context, args struct {
 		data:    result.Result,
 		gasUsed: hexutil.Uint64(result.UsedGas),
 		status:  status,
-	}, err
+	}, nil
 }
 
 func (p *Pending) EstimateGas(ctx context.Context, args struct {
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index c319b5bb20..e5a61aee12 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -916,9 +916,9 @@ func DoEstimateGas(ctx context.Context, b Backend, args CallArgs, blockNrOrHash
 		result, err := DoCall(ctx, b, args, blockNrOrHash, nil, vm.Config{}, 0, gasCap)
 		if err != nil {
 			if err == core.ErrInsufficientIntrinsicGas {
-				return true, nil, nil
+				return true, nil, nil // Special case, raise gas limit
 			}
-			return true, nil, err
+			return true, nil, err // Bail out
 		}
 		return result.Failed(), result, nil
 	}
@@ -946,9 +946,17 @@ func DoEstimateGas(ctx context.Context, b Backend, args CallArgs, blockNrOrHash
 			return 0, err
 		}
 		if failed {
-			if result != nil && len(result.RevertReason) != 0 {
-				return 0, fmt.Errorf("Reverted %x", result.RevertReason)
+			if result != nil {
+				// If the revert reason is provided, return it to user.
+				if result.Err == vm.ErrExecutionReverted {
+					return 0, fmt.Errorf("transaction reverted (0x%x)", result.RevertReason)
+				}
+				// If it's an invalid transaction, return the concrete vm error
+				if result.Err != vm.ErrOutOfGas {
+					return 0, fmt.Errorf("always failing transaction (%v)", result.Err)
+				}
 			}
+			// Otherwise, the specified gas cap is too low
 			return 0, fmt.Errorf("gas required exceeds allowance (%d)", cap)
 		}
 	}