diff --git a/internal/encoding/encoding.go b/internal/encoding/encoding.go
index 8c173f51b9..fba7f33dad 100644
--- a/internal/encoding/encoding.go
+++ b/internal/encoding/encoding.go
@@ -45,7 +45,13 @@ func (h HexBytes) MarshalJSON() ([]byte, error) {
 func (h *HexBytes) UnmarshalYAML(unmarshal func(any) error) error {
 	var hexString string
 	if err := unmarshal(&hexString); err != nil {
-		return err
+		// compatibility mode for old state file format:
+		// fall back to unmarshalling as a byte slice for backwards compatibility
+		var oldHexBytes []byte
+		if err := unmarshal(&oldHexBytes); err != nil {
+			return fmt.Errorf("unmarshalling hex bytes: %w", err)
+		}
+		hexString = hex.EncodeToString(oldHexBytes)
 	}
 	return h.unmarshal(hexString)
 }
diff --git a/internal/encoding/encoding_test.go b/internal/encoding/encoding_test.go
index 3e14914ebb..0c6e4a1304 100644
--- a/internal/encoding/encoding_test.go
+++ b/internal/encoding/encoding_test.go
@@ -76,6 +76,16 @@ func TestUnmarshalHexBytes(t *testing.T) {
 			jsonString: "\"\"",
 			expected:   nil,
 		},
+		"byte slice compat": {
+			yamlString: "[0xab, 0xcd, 0xef]",
+			jsonString: "\"abcdef\"", // no backwards compatibility since we never used this format for json
+			expected:   []byte{0xab, 0xcd, 0xef},
+		},
+		"byte slice compat 2": {
+			yamlString: "[00, 12, 34]",
+			jsonString: "\"000c22\"", // no backwards compatibility since we never used this format for json
+			expected:   []byte{0x00, 0x0c, 0x22},
+		},
 	}
 
 	for name, tc := range testCases {