diff --git a/internal/compiler/analyze.go b/internal/compiler/analyze.go
index 0d7d507575..264dbef6f5 100644
--- a/internal/compiler/analyze.go
+++ b/internal/compiler/analyze.go
@@ -144,14 +144,14 @@ func (c *Compiler) _analyzeQuery(raw *ast.RawStmt, query string, failfast bool)
 	var table *ast.TableName
 	switch n := raw.Stmt.(type) {
 	case *ast.InsertStmt:
-		if err := check(validate.InsertStmt(n)); err != nil {
-			return nil, err
-		}
 		var err error
 		table, err = ParseTableName(n.Relation)
 		if err := check(err); err != nil {
 			return nil, err
 		}
+		if err := check(validate.InsertStmt(c.catalog, table, n)); err != nil {
+			return nil, err
+		}
 	}
 
 	if err := check(validate.FuncCall(c.catalog, c.combo, raw)); err != nil {
diff --git a/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/exec.json b/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/exec.json
index ee1b7ecd9e..2e996ca79d 100644
--- a/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/exec.json
+++ b/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/exec.json
@@ -1,3 +1,3 @@
 {
-  "contexts": ["managed-db"]
+  "contexts": ["base"]
 }
diff --git a/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/query.sql b/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/query.sql
index 3f9e9d9b86..2484d998b6 100644
--- a/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/query.sql
+++ b/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/query.sql
@@ -1,4 +1,23 @@
--- name: UpsertServer :exec
-INSERT INTO servers(code, name) VALUES ($1, $2) 
-ON CONFLICT (code) 
-DO UPDATE SET name_typo = 1111;
\ No newline at end of file
+-- name: UpsertServerSetColumnTypo :exec
+INSERT INTO servers(code, name) VALUES ($1, $2)
+ON CONFLICT (code)
+DO UPDATE SET name_typo = 1111;
+
+-- name: UpsertServerConflictTargetTypo :exec
+INSERT INTO servers(code, name) VALUES ($1, $2)
+ON CONFLICT (code_typo)
+DO UPDATE SET name = 1111;
+
+-- name: UpsertServerExcludedColumnTypo :exec
+INSERT INTO servers(code, name) VALUES ($1, $2)
+ON CONFLICT (code)
+DO UPDATE SET name = EXCLUDED.name_typo;
+
+-- name: UpsertServerMissingConflictTarget :exec
+INSERT INTO servers(code, name) VALUES ($1, $2)
+ON CONFLICT DO UPDATE SET name = EXCLUDED.name;
+
+-- name: UpsertServerOnConstraintExcludedTypo :exec
+INSERT INTO servers(code, name) VALUES ($1, $2)
+ON CONFLICT ON CONSTRAINT servers_pkey DO UPDATE SET name = EXCLUDED.name_typo;
+
diff --git a/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/schema.sql b/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/schema.sql
index 3ff1ccd6b3..c3dec12e49 100644
--- a/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/schema.sql
+++ b/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/schema.sql
@@ -1,4 +1,4 @@
 CREATE TABLE servers (
-  code varchar   PRIMARY KEY,
-  name text      NOT NULL
-);
\ No newline at end of file
+  code    varchar PRIMARY KEY,
+  name    text    NOT NULL
+);
diff --git a/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/stderr.txt b/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/stderr.txt
index adbb13a418..b9692daa64 100644
--- a/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/stderr.txt
+++ b/internal/endtoend/testdata/update_set_on_conflict/postgresql/pgx/stderr.txt
@@ -1,2 +1,6 @@
 # package querytest
-query.sql:4:15: column "name_typo" of relation "servers" does not exist
\ No newline at end of file
+query.sql:4:15: column "name_typo" of relation "servers" does not exist
+query.sql:8:13: column "code_typo" of relation "servers" does not exist
+query.sql:14:22: column "name_typo" of relation "EXCLUDED" does not exist
+query.sql:17:1: ON CONFLICT DO UPDATE requires inference specification or constraint name
+query.sql:22:61: column "name_typo" of relation "EXCLUDED" does not exist
diff --git a/internal/sql/validate/insert_stmt.go b/internal/sql/validate/insert_stmt.go
index dd8041ea23..236ddbfceb 100644
--- a/internal/sql/validate/insert_stmt.go
+++ b/internal/sql/validate/insert_stmt.go
@@ -1,11 +1,16 @@
 package validate
 
 import (
+	"strings"
+
 	"github.com/sqlc-dev/sqlc/internal/sql/ast"
+	"github.com/sqlc-dev/sqlc/internal/sql/catalog"
 	"github.com/sqlc-dev/sqlc/internal/sql/sqlerr"
 )
 
-func InsertStmt(stmt *ast.InsertStmt) error {
+const excludedTable = "EXCLUDED"
+
+func InsertStmt(c *catalog.Catalog, fqn *ast.TableName, stmt *ast.InsertStmt) error {
 	sel, ok := stmt.SelectStmt.(*ast.SelectStmt)
 	if !ok {
 		return nil
@@ -35,5 +40,102 @@ func InsertStmt(stmt *ast.InsertStmt) error {
 			Message: "INSERT has more expressions than target columns",
 		}
 	}
+
+	return onConflictClause(c, fqn, stmt)
+}
+
+// onConflictClause validates an ON CONFLICT DO UPDATE clause against the target
+// table. It checks:
+//   - ON CONFLICT (col, ...) conflict target columns exist
+//   - DO UPDATE SET col = ... assignment target columns exist
+//   - EXCLUDED.col references exist
+func onConflictClause(c *catalog.Catalog, fqn *ast.TableName, n *ast.InsertStmt) error {
+	if fqn == nil || n.OnConflictClause == nil || n.OnConflictClause.Action != ast.OnConflictActionUpdate {
+		return nil
+	}
+
+	table, err := c.GetTable(fqn)
+	if err != nil {
+		return err
+	}
+
+	// Build set of column names for existence checks.
+	colNames := make(map[string]struct{}, len(table.Columns))
+	for _, col := range table.Columns {
+		colNames[col.Name] = struct{}{}
+	}
+
+	// DO UPDATE requires a conflict target: ON CONFLICT (col) or ON CONFLICT ON CONSTRAINT name.
+	if n.OnConflictClause.Infer == nil {
+		return &sqlerr.Error{
+			Code:    "42601",
+			Message: "ON CONFLICT DO UPDATE requires inference specification or constraint name",
+		}
+	}
+
+	// Validate ON CONFLICT (col, ...) conflict target columns.
+	if n.OnConflictClause.Infer.IndexElems != nil {
+		for _, item := range n.OnConflictClause.Infer.IndexElems.Items {
+			elem, ok := item.(*ast.IndexElem)
+			if !ok || elem.Name == nil {
+				continue
+			}
+
+			if _, exists := colNames[*elem.Name]; !exists {
+				e := sqlerr.ColumnNotFound(table.Rel.Name, *elem.Name)
+				e.Location = n.OnConflictClause.Infer.Location
+				return e
+			}
+		}
+	}
+
+	// Validate DO UPDATE SET col = ... assignment target columns and EXCLUDED.col references.
+	if n.OnConflictClause.TargetList == nil {
+		return nil
+	}
+
+	for _, item := range n.OnConflictClause.TargetList.Items {
+		target, ok := item.(*ast.ResTarget)
+		if !ok || target.Name == nil {
+			continue
+		}
+
+		if _, exists := colNames[*target.Name]; !exists {
+			e := sqlerr.ColumnNotFound(table.Rel.Name, *target.Name)
+			e.Location = target.Location
+			return e
+		}
+
+		if ref, ok := target.Val.(*ast.ColumnRef); ok {
+			if excludedCol, ok := excludedColumnRef(ref); ok {
+				if _, exists := colNames[excludedCol]; !exists {
+					e := sqlerr.ColumnNotFound(excludedTable, excludedCol)
+					e.Location = ref.Location
+					return e
+				}
+			}
+		}
+	}
+
 	return nil
 }
+
+// excludedColumnRef returns the column name if the ColumnRef is an EXCLUDED.col
+// reference, and ok=true. Returns "", false otherwise.
+func excludedColumnRef(ref *ast.ColumnRef) (string, bool) {
+	if ref.Fields == nil || len(ref.Fields.Items) != 2 {
+		return "", false
+	}
+
+	first, ok := ref.Fields.Items[0].(*ast.String)
+	if !ok || !strings.EqualFold(first.Str, excludedTable) {
+		return "", false
+	}
+
+	second, ok := ref.Fields.Items[1].(*ast.String)
+	if !ok {
+		return "", false
+	}
+
+	return second.Str, true
+}