diff --git a/src/encoding/json/decode_test.go b/src/encoding/json/decode_test.go
index 473fd028330..0df31c82c82 100644
--- a/src/encoding/json/decode_test.go
+++ b/src/encoding/json/decode_test.go
@@ -12,6 +12,7 @@ import (
 	"errors"
 	"fmt"
 	"image"
+	"io"
 	"maps"
 	"math"
 	"math/big"
@@ -469,11 +470,13 @@ var unmarshalTests = []struct {
 	{CaseName: Name(""), in: `{"alphabet": "xyz"}`, ptr: new(U), err: fmt.Errorf("json: unknown field \"alphabet\""), disallowUnknownFields: true},
 
 	// syntax errors
+	{CaseName: Name(""), in: ``, ptr: new(any), err: &SyntaxError{"unexpected end of JSON input", 0}},
+	{CaseName: Name(""), in: " \n\r\t", ptr: new(any), err: &SyntaxError{"unexpected end of JSON input", 4}},
+	{CaseName: Name(""), in: `[2, 3`, ptr: new(any), err: &SyntaxError{"unexpected end of JSON input", 5}},
 	{CaseName: Name(""), in: `{"X": "foo", "Y"}`, err: &SyntaxError{"invalid character '}' after object key", 17}},
 	{CaseName: Name(""), in: `[1, 2, 3+]`, err: &SyntaxError{"invalid character '+' after array element", 9}},
 	{CaseName: Name(""), in: `{"X":12x}`, err: &SyntaxError{"invalid character 'x' after object key:value pair", 8}, useNumber: true},
-	{CaseName: Name(""), in: `[2, 3`, err: &SyntaxError{msg: "unexpected end of JSON input", Offset: 5}},
-	{CaseName: Name(""), in: `{"F3": -}`, ptr: new(V), err: &SyntaxError{msg: "invalid character '}' in numeric literal", Offset: 9}},
+	{CaseName: Name(""), in: `{"F3": -}`, ptr: new(V), err: &SyntaxError{"invalid character '}' in numeric literal", 9}},
 
 	// raw value errors
 	{CaseName: Name(""), in: "\x01 42", err: &SyntaxError{"invalid character '\\x01' looking for beginning of value", 1}},
@@ -1377,6 +1380,14 @@ func TestUnmarshal(t *testing.T) {
 			if tt.disallowUnknownFields {
 				dec.DisallowUnknownFields()
 			}
+			if tt.err != nil && strings.Contains(tt.err.Error(), "unexpected end of JSON input") {
+				// In streaming mode, we expect EOF or ErrUnexpectedEOF instead.
+				if strings.TrimSpace(tt.in) == "" {
+					tt.err = io.EOF
+				} else {
+					tt.err = io.ErrUnexpectedEOF
+				}
+			}
 			if err := dec.Decode(v.Interface()); !equalError(err, tt.err) {
 				t.Fatalf("%s: Decode error:\n\tgot:  %v\n\twant: %v\n\n\tgot:  %#v\n\twant: %#v", tt.Where, err, tt.err, err, tt.err)
 			} else if err != nil && tt.out == nil {
diff --git a/src/encoding/json/v2/arshal.go b/src/encoding/json/v2/arshal.go
index 10b16efe4a6..5cd2106be93 100644
--- a/src/encoding/json/v2/arshal.go
+++ b/src/encoding/json/v2/arshal.go
@@ -438,7 +438,8 @@ func unmarshalFull(in *jsontext.Decoder, out any, uo *jsonopts.Struct) error {
 	case nil:
 		return export.Decoder(in).CheckEOF()
 	case io.EOF:
-		return io.ErrUnexpectedEOF
+		offset := in.InputOffset() + int64(len(in.UnreadBuffer()))
+		return &jsontext.SyntacticError{ByteOffset: offset, Err: io.ErrUnexpectedEOF}
 	default:
 		return err
 	}
diff --git a/src/encoding/json/v2/arshal_test.go b/src/encoding/json/v2/arshal_test.go
index 8494deed03b..879a2f3e0d7 100644
--- a/src/encoding/json/v2/arshal_test.go
+++ b/src/encoding/json/v2/arshal_test.go
@@ -7138,7 +7138,13 @@ func TestUnmarshal(t *testing.T) {
 		inBuf:   ``,
 		inVal:   addr(structAll{}),
 		want:    addr(structAll{}),
-		wantErr: io.ErrUnexpectedEOF,
+		wantErr: &jsontext.SyntacticError{Err: io.ErrUnexpectedEOF},
+	}, {
+		name:    jsontest.Name("Structs/Invalid/ErrUnexpectedEOF"),
+		inBuf:   " \n\r\t",
+		inVal:   addr(structAll{}),
+		want:    addr(structAll{}),
+		wantErr: &jsontext.SyntacticError{Err: io.ErrUnexpectedEOF, ByteOffset: len64(" \n\r\t")},
 	}, {
 		name:    jsontest.Name("Structs/Invalid/NestedErrUnexpectedEOF"),
 		inBuf:   `{"Pointer":`,
diff --git a/src/encoding/json/v2_decode_test.go b/src/encoding/json/v2_decode_test.go
index 3ab20e2b5d0..cfcefbfcdc3 100644
--- a/src/encoding/json/v2_decode_test.go
+++ b/src/encoding/json/v2_decode_test.go
@@ -12,6 +12,7 @@ import (
 	"errors"
 	"fmt"
 	"image"
+	"io"
 	"maps"
 	"math"
 	"math/big"
@@ -473,11 +474,13 @@ var unmarshalTests = []struct {
 	{CaseName: Name(""), in: `{"alphabet": "xyz"}`, ptr: new(U), err: fmt.Errorf("json: unknown field \"alphabet\""), disallowUnknownFields: true},
 
 	// syntax errors
+	{CaseName: Name(""), in: ``, ptr: new(any), err: &SyntaxError{errUnexpectedEnd.Error(), 0}},
+	{CaseName: Name(""), in: " \n\r\t", ptr: new(any), err: &SyntaxError{errUnexpectedEnd.Error(), len64(" \n\r\t")}},
+	{CaseName: Name(""), in: `[2, 3`, ptr: new(any), err: &SyntaxError{errUnexpectedEnd.Error(), len64(`[2, 3`)}},
 	{CaseName: Name(""), in: `{"X": "foo", "Y"}`, err: &SyntaxError{"invalid character '}' after object key", len64(`{"X": "foo", "Y"`)}},
 	{CaseName: Name(""), in: `[1, 2, 3+]`, err: &SyntaxError{"invalid character '+' after array element", len64(`[1, 2, 3`)}},
 	{CaseName: Name(""), in: `{"X":12x}`, err: &SyntaxError{"invalid character 'x' after object key:value pair", len64(`{"X":12`)}, useNumber: true},
-	{CaseName: Name(""), in: `[2, 3`, err: &SyntaxError{msg: "unexpected end of JSON input", Offset: len64(`[2, 3`)}},
-	{CaseName: Name(""), in: `{"F3": -}`, ptr: new(V), err: &SyntaxError{msg: "invalid character '}' in numeric literal", Offset: len64(`{"F3": -`)}},
+	{CaseName: Name(""), in: `{"F3": -}`, ptr: new(V), err: &SyntaxError{"invalid character '}' in numeric literal", len64(`{"F3": -`)}},
 
 	// raw value errors
 	{CaseName: Name(""), in: "\x01 42", err: &SyntaxError{"invalid character '\\x01' looking for beginning of value", len64(``)}},
@@ -1382,6 +1385,14 @@ func TestUnmarshal(t *testing.T) {
 			if tt.disallowUnknownFields {
 				dec.DisallowUnknownFields()
 			}
+			if tt.err != nil && strings.Contains(tt.err.Error(), errUnexpectedEnd.Error()) {
+				// In streaming mode, we expect EOF or ErrUnexpectedEOF instead.
+				if strings.TrimSpace(tt.in) == "" {
+					tt.err = io.EOF
+				} else {
+					tt.err = io.ErrUnexpectedEOF
+				}
+			}
 			if err := dec.Decode(v.Interface()); !equalError(err, tt.err) {
 				t.Fatalf("%s: Decode error:\n\tgot:  %v\n\twant: %v\n\n\tgot:  %#v\n\twant: %#v", tt.Where, err, tt.err, err, tt.err)
 			} else if err != nil && tt.out == nil {
diff --git a/src/encoding/json/v2_scanner.go b/src/encoding/json/v2_scanner.go
index 475bf58b209..aef045f466c 100644
--- a/src/encoding/json/v2_scanner.go
+++ b/src/encoding/json/v2_scanner.go
@@ -30,6 +30,10 @@ func checkValid(data []byte) error {
 	xd := export.Decoder(d)
 	xd.Struct.Flags.Set(jsonflags.AllowDuplicateNames | jsonflags.AllowInvalidUTF8 | 1)
 	if _, err := d.ReadValue(); err != nil {
+		if err == io.EOF {
+			offset := d.InputOffset() + int64(len(d.UnreadBuffer()))
+			err = &jsontext.SyntacticError{ByteOffset: offset, Err: io.ErrUnexpectedEOF}
+		}
 		return transformSyntacticError(err)
 	}
 	if err := xd.CheckEOF(); err != nil {
diff --git a/src/encoding/json/v2_stream.go b/src/encoding/json/v2_stream.go
index d58bafbfd0f..ccbef6077bb 100644
--- a/src/encoding/json/v2_stream.go
+++ b/src/encoding/json/v2_stream.go
@@ -68,7 +68,7 @@ func (dec *Decoder) Decode(v any) error {
 	b, err := dec.dec.ReadValue()
 	if err != nil {
 		dec.err = transformSyntacticError(err)
-		if dec.err == errUnexpectedEnd {
+		if dec.err.Error() == errUnexpectedEnd.Error() {
 			// NOTE: Decode has always been inconsistent with Unmarshal
 			// with regard to the exact error value for truncated input.
 			dec.err = io.ErrUnexpectedEOF