From 3f63156b5cb23f5f91661879f591bcc7f50f75c7 Mon Sep 17 00:00:00 2001
From: Vadim Tertilov <vadimtertilov@gmail.com>
Date: Mon, 23 Mar 2026 16:03:31 +0100
Subject: [PATCH] abigenv2: added a package-level error for event signature
 mismatch during unpacking

---
 accounts/abi/abigen/source2.go.tpl            |  5 +++-
 .../abi/abigen/testdata/v2/crowdsale.go.txt   |  5 +++-
 accounts/abi/abigen/testdata/v2/dao.go.txt    | 25 +++++++++++++++----
 .../abigen/testdata/v2/eventchecker.go.txt    | 25 +++++++++++++++----
 .../abigen/testdata/v2/nameconflict.go.txt    |  5 +++-
 .../testdata/v2/numericmethodname.go.txt      |  5 +++-
 .../abi/abigen/testdata/v2/overload.go.txt    | 10 ++++++--
 accounts/abi/abigen/testdata/v2/token.go.txt  |  5 +++-
 accounts/abi/abigen/testdata/v2/tuple.go.txt  | 10 ++++++--
 .../bind/v2/internal/contracts/db/bindings.go | 10 ++++++--
 .../v2/internal/contracts/events/bindings.go  | 10 ++++++--
 11 files changed, 92 insertions(+), 23 deletions(-)

diff --git a/accounts/abi/abigen/source2.go.tpl b/accounts/abi/abigen/source2.go.tpl
index 3d98cbb700..deb27b1437 100644
--- a/accounts/abi/abigen/source2.go.tpl
+++ b/accounts/abi/abigen/source2.go.tpl
@@ -177,6 +177,9 @@ var (
 			return {{$contract.Type}}{{.Normalized.Name}}EventName
 		}
 
+		// Err{{.Normalized.Name}}SignatureMismatch is returned when the event signature does not match the expected signature.
+		var Err{{.Normalized.Name}}SignatureMismatch = errors.New("event signature mismatch")
+
 		// Unpack{{.Normalized.Name}}Event is the Go binding that unpacks the event data emitted
 		// by contract.
 		//
@@ -184,7 +187,7 @@ var (
 		func ({{ decapitalise $contract.Type}} *{{$contract.Type}}) Unpack{{.Normalized.Name}}Event(log *types.Log) (*{{$contract.Type}}{{.Normalized.Name}}, error) {
 			event := "{{.Original.Name}}"
 			if len(log.Topics) == 0 || log.Topics[0] != {{ decapitalise $contract.Type}}.abi.Events[event].ID {
-				return nil, errors.New("event signature mismatch")
+				return nil, Err{{.Normalized.Name}}SignatureMismatch
 			}
 			out := new({{$contract.Type}}{{.Normalized.Name}})
 			if len(log.Data) > 0 {
diff --git a/accounts/abi/abigen/testdata/v2/crowdsale.go.txt b/accounts/abi/abigen/testdata/v2/crowdsale.go.txt
index b548b6cdae..ffe502d9ab 100644
--- a/accounts/abi/abigen/testdata/v2/crowdsale.go.txt
+++ b/accounts/abi/abigen/testdata/v2/crowdsale.go.txt
@@ -354,6 +354,9 @@ func (CrowdsaleFundTransfer) ContractEventName() string {
 	return CrowdsaleFundTransferEventName
 }
 
+// ErrFundTransferSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrFundTransferSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackFundTransferEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -361,7 +364,7 @@ func (CrowdsaleFundTransfer) ContractEventName() string {
 func (crowdsale *Crowdsale) UnpackFundTransferEvent(log *types.Log) (*CrowdsaleFundTransfer, error) {
 	event := "FundTransfer"
 	if len(log.Topics) == 0 || log.Topics[0] != crowdsale.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrFundTransferSignatureMismatch
 	}
 	out := new(CrowdsaleFundTransfer)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/abigen/testdata/v2/dao.go.txt b/accounts/abi/abigen/testdata/v2/dao.go.txt
index c246771d6d..1eef070f89 100644
--- a/accounts/abi/abigen/testdata/v2/dao.go.txt
+++ b/accounts/abi/abigen/testdata/v2/dao.go.txt
@@ -600,6 +600,9 @@ func (DAOChangeOfRules) ContractEventName() string {
 	return DAOChangeOfRulesEventName
 }
 
+// ErrChangeOfRulesSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrChangeOfRulesSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackChangeOfRulesEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -607,7 +610,7 @@ func (DAOChangeOfRules) ContractEventName() string {
 func (dAO *DAO) UnpackChangeOfRulesEvent(log *types.Log) (*DAOChangeOfRules, error) {
 	event := "ChangeOfRules"
 	if len(log.Topics) == 0 || log.Topics[0] != dAO.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrChangeOfRulesSignatureMismatch
 	}
 	out := new(DAOChangeOfRules)
 	if len(log.Data) > 0 {
@@ -642,6 +645,9 @@ func (DAOMembershipChanged) ContractEventName() string {
 	return DAOMembershipChangedEventName
 }
 
+// ErrMembershipChangedSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrMembershipChangedSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackMembershipChangedEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -649,7 +655,7 @@ func (DAOMembershipChanged) ContractEventName() string {
 func (dAO *DAO) UnpackMembershipChangedEvent(log *types.Log) (*DAOMembershipChanged, error) {
 	event := "MembershipChanged"
 	if len(log.Topics) == 0 || log.Topics[0] != dAO.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrMembershipChangedSignatureMismatch
 	}
 	out := new(DAOMembershipChanged)
 	if len(log.Data) > 0 {
@@ -686,6 +692,9 @@ func (DAOProposalAdded) ContractEventName() string {
 	return DAOProposalAddedEventName
 }
 
+// ErrProposalAddedSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrProposalAddedSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackProposalAddedEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -693,7 +702,7 @@ func (DAOProposalAdded) ContractEventName() string {
 func (dAO *DAO) UnpackProposalAddedEvent(log *types.Log) (*DAOProposalAdded, error) {
 	event := "ProposalAdded"
 	if len(log.Topics) == 0 || log.Topics[0] != dAO.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrProposalAddedSignatureMismatch
 	}
 	out := new(DAOProposalAdded)
 	if len(log.Data) > 0 {
@@ -730,6 +739,9 @@ func (DAOProposalTallied) ContractEventName() string {
 	return DAOProposalTalliedEventName
 }
 
+// ErrProposalTalliedSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrProposalTalliedSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackProposalTalliedEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -737,7 +749,7 @@ func (DAOProposalTallied) ContractEventName() string {
 func (dAO *DAO) UnpackProposalTalliedEvent(log *types.Log) (*DAOProposalTallied, error) {
 	event := "ProposalTallied"
 	if len(log.Topics) == 0 || log.Topics[0] != dAO.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrProposalTalliedSignatureMismatch
 	}
 	out := new(DAOProposalTallied)
 	if len(log.Data) > 0 {
@@ -774,6 +786,9 @@ func (DAOVoted) ContractEventName() string {
 	return DAOVotedEventName
 }
 
+// ErrVotedSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrVotedSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackVotedEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -781,7 +796,7 @@ func (DAOVoted) ContractEventName() string {
 func (dAO *DAO) UnpackVotedEvent(log *types.Log) (*DAOVoted, error) {
 	event := "Voted"
 	if len(log.Topics) == 0 || log.Topics[0] != dAO.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrVotedSignatureMismatch
 	}
 	out := new(DAOVoted)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/abigen/testdata/v2/eventchecker.go.txt b/accounts/abi/abigen/testdata/v2/eventchecker.go.txt
index 8ad59e63b1..8a9445c10b 100644
--- a/accounts/abi/abigen/testdata/v2/eventchecker.go.txt
+++ b/accounts/abi/abigen/testdata/v2/eventchecker.go.txt
@@ -66,6 +66,9 @@ func (EventCheckerDynamic) ContractEventName() string {
 	return EventCheckerDynamicEventName
 }
 
+// ErrDynamicSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrDynamicSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackDynamicEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -73,7 +76,7 @@ func (EventCheckerDynamic) ContractEventName() string {
 func (eventChecker *EventChecker) UnpackDynamicEvent(log *types.Log) (*EventCheckerDynamic, error) {
 	event := "dynamic"
 	if len(log.Topics) == 0 || log.Topics[0] != eventChecker.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrDynamicSignatureMismatch
 	}
 	out := new(EventCheckerDynamic)
 	if len(log.Data) > 0 {
@@ -106,6 +109,9 @@ func (EventCheckerEmpty) ContractEventName() string {
 	return EventCheckerEmptyEventName
 }
 
+// ErrEmptySignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrEmptySignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackEmptyEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -113,7 +119,7 @@ func (EventCheckerEmpty) ContractEventName() string {
 func (eventChecker *EventChecker) UnpackEmptyEvent(log *types.Log) (*EventCheckerEmpty, error) {
 	event := "empty"
 	if len(log.Topics) == 0 || log.Topics[0] != eventChecker.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrEmptySignatureMismatch
 	}
 	out := new(EventCheckerEmpty)
 	if len(log.Data) > 0 {
@@ -148,6 +154,9 @@ func (EventCheckerIndexed) ContractEventName() string {
 	return EventCheckerIndexedEventName
 }
 
+// ErrIndexedSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrIndexedSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackIndexedEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -155,7 +164,7 @@ func (EventCheckerIndexed) ContractEventName() string {
 func (eventChecker *EventChecker) UnpackIndexedEvent(log *types.Log) (*EventCheckerIndexed, error) {
 	event := "indexed"
 	if len(log.Topics) == 0 || log.Topics[0] != eventChecker.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrIndexedSignatureMismatch
 	}
 	out := new(EventCheckerIndexed)
 	if len(log.Data) > 0 {
@@ -190,6 +199,9 @@ func (EventCheckerMixed) ContractEventName() string {
 	return EventCheckerMixedEventName
 }
 
+// ErrMixedSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrMixedSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackMixedEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -197,7 +209,7 @@ func (EventCheckerMixed) ContractEventName() string {
 func (eventChecker *EventChecker) UnpackMixedEvent(log *types.Log) (*EventCheckerMixed, error) {
 	event := "mixed"
 	if len(log.Topics) == 0 || log.Topics[0] != eventChecker.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrMixedSignatureMismatch
 	}
 	out := new(EventCheckerMixed)
 	if len(log.Data) > 0 {
@@ -232,6 +244,9 @@ func (EventCheckerUnnamed) ContractEventName() string {
 	return EventCheckerUnnamedEventName
 }
 
+// ErrUnnamedSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrUnnamedSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackUnnamedEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -239,7 +254,7 @@ func (EventCheckerUnnamed) ContractEventName() string {
 func (eventChecker *EventChecker) UnpackUnnamedEvent(log *types.Log) (*EventCheckerUnnamed, error) {
 	event := "unnamed"
 	if len(log.Topics) == 0 || log.Topics[0] != eventChecker.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrUnnamedSignatureMismatch
 	}
 	out := new(EventCheckerUnnamed)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/abigen/testdata/v2/nameconflict.go.txt b/accounts/abi/abigen/testdata/v2/nameconflict.go.txt
index 3fbabee5a5..28ce0cece0 100644
--- a/accounts/abi/abigen/testdata/v2/nameconflict.go.txt
+++ b/accounts/abi/abigen/testdata/v2/nameconflict.go.txt
@@ -128,6 +128,9 @@ func (NameConflictLog) ContractEventName() string {
 	return NameConflictLogEventName
 }
 
+// ErrLogSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrLogSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackLogEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -135,7 +138,7 @@ func (NameConflictLog) ContractEventName() string {
 func (nameConflict *NameConflict) UnpackLogEvent(log *types.Log) (*NameConflictLog, error) {
 	event := "log"
 	if len(log.Topics) == 0 || log.Topics[0] != nameConflict.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrLogSignatureMismatch
 	}
 	out := new(NameConflictLog)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/abigen/testdata/v2/numericmethodname.go.txt b/accounts/abi/abigen/testdata/v2/numericmethodname.go.txt
index d962583e48..18ba56a3da 100644
--- a/accounts/abi/abigen/testdata/v2/numericmethodname.go.txt
+++ b/accounts/abi/abigen/testdata/v2/numericmethodname.go.txt
@@ -130,6 +130,9 @@ func (NumericMethodNameE1TestEvent) ContractEventName() string {
 	return NumericMethodNameE1TestEventEventName
 }
 
+// ErrE1TestEventSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrE1TestEventSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackE1TestEventEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -137,7 +140,7 @@ func (NumericMethodNameE1TestEvent) ContractEventName() string {
 func (numericMethodName *NumericMethodName) UnpackE1TestEventEvent(log *types.Log) (*NumericMethodNameE1TestEvent, error) {
 	event := "_1TestEvent"
 	if len(log.Topics) == 0 || log.Topics[0] != numericMethodName.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrE1TestEventSignatureMismatch
 	}
 	out := new(NumericMethodNameE1TestEvent)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/abigen/testdata/v2/overload.go.txt b/accounts/abi/abigen/testdata/v2/overload.go.txt
index ddddd10186..a02dadf903 100644
--- a/accounts/abi/abigen/testdata/v2/overload.go.txt
+++ b/accounts/abi/abigen/testdata/v2/overload.go.txt
@@ -108,6 +108,9 @@ func (OverloadBar) ContractEventName() string {
 	return OverloadBarEventName
 }
 
+// ErrBarSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrBarSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackBarEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -115,7 +118,7 @@ func (OverloadBar) ContractEventName() string {
 func (overload *Overload) UnpackBarEvent(log *types.Log) (*OverloadBar, error) {
 	event := "bar"
 	if len(log.Topics) == 0 || log.Topics[0] != overload.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrBarSignatureMismatch
 	}
 	out := new(OverloadBar)
 	if len(log.Data) > 0 {
@@ -150,6 +153,9 @@ func (OverloadBar0) ContractEventName() string {
 	return OverloadBar0EventName
 }
 
+// ErrBar0SignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrBar0SignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackBar0Event is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -157,7 +163,7 @@ func (OverloadBar0) ContractEventName() string {
 func (overload *Overload) UnpackBar0Event(log *types.Log) (*OverloadBar0, error) {
 	event := "bar0"
 	if len(log.Topics) == 0 || log.Topics[0] != overload.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrBar0SignatureMismatch
 	}
 	out := new(OverloadBar0)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/abigen/testdata/v2/token.go.txt b/accounts/abi/abigen/testdata/v2/token.go.txt
index 6ebc96861b..136fbd499d 100644
--- a/accounts/abi/abigen/testdata/v2/token.go.txt
+++ b/accounts/abi/abigen/testdata/v2/token.go.txt
@@ -380,6 +380,9 @@ func (TokenTransfer) ContractEventName() string {
 	return TokenTransferEventName
 }
 
+// ErrTransferSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrTransferSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackTransferEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -387,7 +390,7 @@ func (TokenTransfer) ContractEventName() string {
 func (token *Token) UnpackTransferEvent(log *types.Log) (*TokenTransfer, error) {
 	event := "Transfer"
 	if len(log.Topics) == 0 || log.Topics[0] != token.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrTransferSignatureMismatch
 	}
 	out := new(TokenTransfer)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/abigen/testdata/v2/tuple.go.txt b/accounts/abi/abigen/testdata/v2/tuple.go.txt
index 4724fdd351..e190863044 100644
--- a/accounts/abi/abigen/testdata/v2/tuple.go.txt
+++ b/accounts/abi/abigen/testdata/v2/tuple.go.txt
@@ -187,6 +187,9 @@ func (TupleTupleEvent) ContractEventName() string {
 	return TupleTupleEventEventName
 }
 
+// ErrTupleEventSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrTupleEventSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackTupleEventEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -194,7 +197,7 @@ func (TupleTupleEvent) ContractEventName() string {
 func (tuple *Tuple) UnpackTupleEventEvent(log *types.Log) (*TupleTupleEvent, error) {
 	event := "TupleEvent"
 	if len(log.Topics) == 0 || log.Topics[0] != tuple.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrTupleEventSignatureMismatch
 	}
 	out := new(TupleTupleEvent)
 	if len(log.Data) > 0 {
@@ -228,6 +231,9 @@ func (TupleTupleEvent2) ContractEventName() string {
 	return TupleTupleEvent2EventName
 }
 
+// ErrTupleEvent2SignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrTupleEvent2SignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackTupleEvent2Event is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -235,7 +241,7 @@ func (TupleTupleEvent2) ContractEventName() string {
 func (tuple *Tuple) UnpackTupleEvent2Event(log *types.Log) (*TupleTupleEvent2, error) {
 	event := "TupleEvent2"
 	if len(log.Topics) == 0 || log.Topics[0] != tuple.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrTupleEvent2SignatureMismatch
 	}
 	out := new(TupleTupleEvent2)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/bind/v2/internal/contracts/db/bindings.go b/accounts/abi/bind/v2/internal/contracts/db/bindings.go
index 4ac1652ff7..dc72fea6ad 100644
--- a/accounts/abi/bind/v2/internal/contracts/db/bindings.go
+++ b/accounts/abi/bind/v2/internal/contracts/db/bindings.go
@@ -270,6 +270,9 @@ func (DBInsert) ContractEventName() string {
 	return DBInsertEventName
 }
 
+// ErrInsertSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrInsertSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackInsertEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -277,7 +280,7 @@ func (DBInsert) ContractEventName() string {
 func (dB *DB) UnpackInsertEvent(log *types.Log) (*DBInsert, error) {
 	event := "Insert"
 	if len(log.Topics) == 0 || log.Topics[0] != dB.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrInsertSignatureMismatch
 	}
 	out := new(DBInsert)
 	if len(log.Data) > 0 {
@@ -312,6 +315,9 @@ func (DBKeyedInsert) ContractEventName() string {
 	return DBKeyedInsertEventName
 }
 
+// ErrKeyedInsertSignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrKeyedInsertSignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackKeyedInsertEvent is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -319,7 +325,7 @@ func (DBKeyedInsert) ContractEventName() string {
 func (dB *DB) UnpackKeyedInsertEvent(log *types.Log) (*DBKeyedInsert, error) {
 	event := "KeyedInsert"
 	if len(log.Topics) == 0 || log.Topics[0] != dB.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrKeyedInsertSignatureMismatch
 	}
 	out := new(DBKeyedInsert)
 	if len(log.Data) > 0 {
diff --git a/accounts/abi/bind/v2/internal/contracts/events/bindings.go b/accounts/abi/bind/v2/internal/contracts/events/bindings.go
index 40d2c44a44..2d7639ff9c 100644
--- a/accounts/abi/bind/v2/internal/contracts/events/bindings.go
+++ b/accounts/abi/bind/v2/internal/contracts/events/bindings.go
@@ -109,6 +109,9 @@ func (CBasic1) ContractEventName() string {
 	return CBasic1EventName
 }
 
+// ErrBasic1SignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrBasic1SignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackBasic1Event is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -116,7 +119,7 @@ func (CBasic1) ContractEventName() string {
 func (c *C) UnpackBasic1Event(log *types.Log) (*CBasic1, error) {
 	event := "basic1"
 	if len(log.Topics) == 0 || log.Topics[0] != c.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrBasic1SignatureMismatch
 	}
 	out := new(CBasic1)
 	if len(log.Data) > 0 {
@@ -151,6 +154,9 @@ func (CBasic2) ContractEventName() string {
 	return CBasic2EventName
 }
 
+// ErrBasic2SignatureMismatch is returned when the event signature does not match the expected signature.
+var ErrBasic2SignatureMismatch = errors.New("event signature mismatch")
+
 // UnpackBasic2Event is the Go binding that unpacks the event data emitted
 // by contract.
 //
@@ -158,7 +164,7 @@ func (CBasic2) ContractEventName() string {
 func (c *C) UnpackBasic2Event(log *types.Log) (*CBasic2, error) {
 	event := "basic2"
 	if len(log.Topics) == 0 || log.Topics[0] != c.abi.Events[event].ID {
-		return nil, errors.New("event signature mismatch")
+		return nil, ErrBasic2SignatureMismatch
 	}
 	out := new(CBasic2)
 	if len(log.Data) > 0 {