diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0a6451b90b..f56bf2ea4d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,12 @@
 # CHANGELOG
 
-## master
+## 6.4.2 Oct 18, 2021
+
+Upgrade priority: Low. Recommended for Westmint runtime 500+
 
 Changes:
 
+- Ensure `SignerPayload` correctly serializes `Option` with `None`
 - Add Ethereum `BlockV{0, 1, 2}` types, aligning with latest Frontier
 - Additional tests for metadata serialization/de-serialization
 
diff --git a/package.json b/package.json
index c468d26136..66caef1c04 100644
--- a/package.json
+++ b/package.json
@@ -35,6 +35,6 @@
     "@types/jest": "^27.0.2",
     "copyfiles": "^2.4.1"
   },
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "packageManager": "yarn@3.0.1"
 }
diff --git a/packages/api-contract/package.json b/packages/api-contract/package.json
index 5a63618742..dce8cd8714 100644
--- a/packages/api-contract/package.json
+++ b/packages/api-contract/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/api-contract",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "Interfaces for interacting with contracts and contract ABIs",
   "main": "index.js",
@@ -20,8 +20,8 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/api-contract#readme",
   "dependencies": {
     "@babel/runtime": "^7.15.4",
-    "@polkadot/api": "6.4.2-1",
-    "@polkadot/types": "6.4.2-1",
+    "@polkadot/api": "6.4.2",
+    "@polkadot/types": "6.4.2",
     "@polkadot/util": "^7.5.1",
     "rxjs": "^7.4.0"
   }
diff --git a/packages/api-derive/package.json b/packages/api-derive/package.json
index dd7ec06fec..273cb57e21 100644
--- a/packages/api-derive/package.json
+++ b/packages/api-derive/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/api-derive",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "Common functions used across Polkadot, derived from RPC calls and storage queries.",
   "main": "index.js",
@@ -20,15 +20,15 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/api-derive#readme",
   "dependencies": {
     "@babel/runtime": "^7.15.4",
-    "@polkadot/api": "6.4.2-1",
-    "@polkadot/rpc-core": "6.4.2-1",
-    "@polkadot/types": "6.4.2-1",
+    "@polkadot/api": "6.4.2",
+    "@polkadot/rpc-core": "6.4.2",
+    "@polkadot/types": "6.4.2",
     "@polkadot/util": "^7.5.1",
     "@polkadot/util-crypto": "^7.5.1",
     "rxjs": "^7.4.0"
   },
   "devDependencies": {
     "@polkadot/keyring": "^7.5.1",
-    "@polkadot/rpc-provider": "6.4.2-1"
+    "@polkadot/rpc-provider": "6.4.2"
   }
 }
diff --git a/packages/api/package.json b/packages/api/package.json
index 5ce66cbee1..c8b4cd59fe 100644
--- a/packages/api/package.json
+++ b/packages/api/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/api",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "Promise and RxJS wrappers around the Polkadot JS RPC",
   "main": "index.js",
@@ -20,12 +20,12 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/api#readme",
   "dependencies": {
     "@babel/runtime": "^7.15.4",
-    "@polkadot/api-derive": "6.4.2-1",
+    "@polkadot/api-derive": "6.4.2",
     "@polkadot/keyring": "^7.5.1",
-    "@polkadot/rpc-core": "6.4.2-1",
-    "@polkadot/rpc-provider": "6.4.2-1",
-    "@polkadot/types": "6.4.2-1",
-    "@polkadot/types-known": "6.4.2-1",
+    "@polkadot/rpc-core": "6.4.2",
+    "@polkadot/rpc-provider": "6.4.2",
+    "@polkadot/types": "6.4.2",
+    "@polkadot/types-known": "6.4.2",
     "@polkadot/util": "^7.5.1",
     "@polkadot/util-crypto": "^7.5.1",
     "eventemitter3": "^4.0.7",
diff --git a/packages/rpc-core/package.json b/packages/rpc-core/package.json
index 8a6ccecd8e..4000d5973d 100644
--- a/packages/rpc-core/package.json
+++ b/packages/rpc-core/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/rpc-core",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "A JavaScript wrapper for the Polkadot JsonRPC interface",
   "main": "index.js",
@@ -20,8 +20,8 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/rpc-core#readme",
   "dependencies": {
     "@babel/runtime": "^7.15.4",
-    "@polkadot/rpc-provider": "6.4.2-1",
-    "@polkadot/types": "6.4.2-1",
+    "@polkadot/rpc-provider": "6.4.2",
+    "@polkadot/types": "6.4.2",
     "@polkadot/util": "^7.5.1",
     "rxjs": "^7.4.0"
   },
diff --git a/packages/rpc-provider/package.json b/packages/rpc-provider/package.json
index f48ae5813d..45c5eae996 100644
--- a/packages/rpc-provider/package.json
+++ b/packages/rpc-provider/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/rpc-provider",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "Transport providers for the API",
   "main": "index.js",
@@ -20,7 +20,7 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/rpc-provider#readme",
   "dependencies": {
     "@babel/runtime": "^7.15.4",
-    "@polkadot/types": "6.4.2-1",
+    "@polkadot/types": "6.4.2",
     "@polkadot/util": "^7.5.1",
     "@polkadot/util-crypto": "^7.5.1",
     "@polkadot/x-fetch": "^7.5.1",
@@ -30,7 +30,7 @@
   },
   "devDependencies": {
     "@polkadot/keyring": "^7.5.1",
-    "@polkadot/types": "6.4.2-1",
+    "@polkadot/types": "6.4.2",
     "mock-socket": "^9.0.5",
     "nock": "^13.1.3"
   }
diff --git a/packages/typegen/package.json b/packages/typegen/package.json
index ee96995a7a..80d8dc79c8 100644
--- a/packages/typegen/package.json
+++ b/packages/typegen/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/typegen",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "Type generation scripts",
   "main": "index.js",
@@ -29,10 +29,10 @@
     "@babel/core": "^7.15.8",
     "@babel/register": "^7.15.3",
     "@babel/runtime": "^7.15.4",
-    "@polkadot/api": "6.4.2-1",
-    "@polkadot/rpc-provider": "6.4.2-1",
-    "@polkadot/types": "6.4.2-1",
-    "@polkadot/types-support": "6.4.2-1",
+    "@polkadot/api": "6.4.2",
+    "@polkadot/rpc-provider": "6.4.2",
+    "@polkadot/types": "6.4.2",
+    "@polkadot/types-support": "6.4.2",
     "@polkadot/util": "^7.5.1",
     "handlebars": "^4.7.7",
     "websocket": "^1.0.34",
diff --git a/packages/types-known/package.json b/packages/types-known/package.json
index 8450f47efa..356b101581 100644
--- a/packages/types-known/package.json
+++ b/packages/types-known/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/types-known",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "Known type definitions",
   "main": "index.js",
@@ -21,7 +21,7 @@
   "dependencies": {
     "@babel/runtime": "^7.15.4",
     "@polkadot/networks": "^7.5.1",
-    "@polkadot/types": "6.4.2-1",
+    "@polkadot/types": "6.4.2",
     "@polkadot/util": "^7.5.1"
   }
 }
diff --git a/packages/types-support/package.json b/packages/types-support/package.json
index 7f5c5eb8ef..99a8f8b638 100644
--- a/packages/types-support/package.json
+++ b/packages/types-support/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/types-support",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "Supporting files for types, mostly for testing",
   "main": "index.js",
diff --git a/packages/types/package.json b/packages/types/package.json
index 81f13fa3db..90a61c584b 100644
--- a/packages/types/package.json
+++ b/packages/types/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/types",
-  "version": "6.4.2-1",
+  "version": "6.4.2",
   "type": "module",
   "description": "Implementation of the Parity codec",
   "main": "index.js",
@@ -26,7 +26,7 @@
   },
   "devDependencies": {
     "@polkadot/keyring": "^7.5.1",
-    "@polkadot/types-support": "6.4.2-1",
+    "@polkadot/types-support": "6.4.2",
     "@types/bn.js": "^4.11.6",
     "bn.js": "^4.12.0"
   }
diff --git a/packages/types/src/codec/Option.spec.ts b/packages/types/src/codec/Option.spec.ts
index cd71a706f7..217bfe3a21 100644
--- a/packages/types/src/codec/Option.spec.ts
+++ b/packages/types/src/codec/Option.spec.ts
@@ -27,6 +27,7 @@ describe('Option', (): void => {
     expect(new Option(registry, Text, undefined).isNone).toBe(true);
     expect(new Option(registry, Text, null).isNone).toBe(true);
     expect(new Option(registry, Text, 'test').isNone).toBe(false);
+    expect(new Option(registry, Text, '0x').isNone).toBe(true);
   });
 
   it('converts an option to an option', (): void => {
diff --git a/packages/types/src/codec/Option.ts b/packages/types/src/codec/Option.ts
index 6e07c40274..87aa809c4d 100644
--- a/packages/types/src/codec/Option.ts
+++ b/packages/types/src/codec/Option.ts
@@ -18,7 +18,7 @@ function decodeOptionU8a (registry: Registry, Type: Constructor, value: Uint8Arr
 
 /** @internal */
 function decodeOption (registry: Registry, typeName: Constructor | string, value?: unknown): Codec {
-  if (isNull(value) || isUndefined(value) || value instanceof Null) {
+  if (isNull(value) || isUndefined(value) || value instanceof Null || value === '0x') {
     return new Null(registry);
   }
 
diff --git a/packages/types/src/create/registry.ts b/packages/types/src/create/registry.ts
index a2e4e12d5c..a3f9e1701d 100644
--- a/packages/types/src/create/registry.ts
+++ b/packages/types/src/create/registry.ts
@@ -459,9 +459,9 @@ export class TypeRegistry implements Registry {
     // setup the available extensions
     this.setSignedExtensions(
       signedExtensions || (
-        metadata.asLatest.extrinsic.version.gt(BN_ZERO)
+        this.#metadata.extrinsic.version.gt(BN_ZERO)
           // FIXME Use the extension and their injected types
-          ? metadata.asLatest.extrinsic.signedExtensions.map(({ identifier }) => identifier.toString())
+          ? this.#metadata.extrinsic.signedExtensions.map(({ identifier }) => identifier.toString())
           : fallbackExtensions
       ),
       userExtensions
diff --git a/packages/types/src/extrinsic/SignerPayload.ts b/packages/types/src/extrinsic/SignerPayload.ts
index 6287602ba7..f6a81684b8 100644
--- a/packages/types/src/extrinsic/SignerPayload.ts
+++ b/packages/types/src/extrinsic/SignerPayload.ts
@@ -7,6 +7,7 @@ import type { Codec, ISignerPayload, Registry, SignerPayloadJSON, SignerPayloadR
 import { u8aToHex } from '@polkadot/util';
 
 import { Compact } from '../codec/Compact';
+import { Option } from '../codec/Option';
 import { Struct } from '../codec/Struct';
 import { Vec } from '../codec/Vec';
 import { Text } from '../primitive/Text';
@@ -120,7 +121,13 @@ export class GenericSignerPayload extends Struct implements ISignerPayload, Sign
     return {
       // add any explicit overrides we may have
       ...(Object.keys(this._extraTypes).reduce<Record<string, string>>((map, key) => {
-        map[key] = (this.get(key) as Codec).toHex();
+        const value = this.get(key) as Codec;
+        const isOption = value instanceof Option;
+
+        // Don't include Option.isNone
+        if (!isOption || value.isSome) {
+          map[key] = value.toHex();
+        }
 
         return map;
       }, {})),
diff --git a/yarn.lock b/yarn.lock
index 2faa0e3ff2..1bbb884ab8 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1833,40 +1833,40 @@ __metadata:
   resolution: "@polkadot/api-contract@workspace:packages/api-contract"
   dependencies:
     "@babel/runtime": ^7.15.4
-    "@polkadot/api": 6.4.2-1
-    "@polkadot/types": 6.4.2-1
+    "@polkadot/api": 6.4.2
+    "@polkadot/types": 6.4.2
     "@polkadot/util": ^7.5.1
     rxjs: ^7.4.0
   languageName: unknown
   linkType: soft
 
-"@polkadot/api-derive@6.4.2-1, @polkadot/api-derive@workspace:packages/api-derive":
+"@polkadot/api-derive@6.4.2, @polkadot/api-derive@workspace:packages/api-derive":
   version: 0.0.0-use.local
   resolution: "@polkadot/api-derive@workspace:packages/api-derive"
   dependencies:
     "@babel/runtime": ^7.15.4
-    "@polkadot/api": 6.4.2-1
+    "@polkadot/api": 6.4.2
     "@polkadot/keyring": ^7.5.1
-    "@polkadot/rpc-core": 6.4.2-1
-    "@polkadot/rpc-provider": 6.4.2-1
-    "@polkadot/types": 6.4.2-1
+    "@polkadot/rpc-core": 6.4.2
+    "@polkadot/rpc-provider": 6.4.2
+    "@polkadot/types": 6.4.2
     "@polkadot/util": ^7.5.1
     "@polkadot/util-crypto": ^7.5.1
     rxjs: ^7.4.0
   languageName: unknown
   linkType: soft
 
-"@polkadot/api@6.4.2-1, @polkadot/api@workspace:packages/api":
+"@polkadot/api@6.4.2, @polkadot/api@workspace:packages/api":
   version: 0.0.0-use.local
   resolution: "@polkadot/api@workspace:packages/api"
   dependencies:
     "@babel/runtime": ^7.15.4
-    "@polkadot/api-derive": 6.4.2-1
+    "@polkadot/api-derive": 6.4.2
     "@polkadot/keyring": ^7.5.1
-    "@polkadot/rpc-core": 6.4.2-1
-    "@polkadot/rpc-provider": 6.4.2-1
-    "@polkadot/types": 6.4.2-1
-    "@polkadot/types-known": 6.4.2-1
+    "@polkadot/rpc-core": 6.4.2
+    "@polkadot/rpc-provider": 6.4.2
+    "@polkadot/types": 6.4.2
+    "@polkadot/types-known": 6.4.2
     "@polkadot/util": ^7.5.1
     "@polkadot/util-crypto": ^7.5.1
     eventemitter3: ^4.0.7
@@ -1991,26 +1991,26 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@polkadot/rpc-core@6.4.2-1, @polkadot/rpc-core@workspace:packages/rpc-core":
+"@polkadot/rpc-core@6.4.2, @polkadot/rpc-core@workspace:packages/rpc-core":
   version: 0.0.0-use.local
   resolution: "@polkadot/rpc-core@workspace:packages/rpc-core"
   dependencies:
     "@babel/runtime": ^7.15.4
     "@polkadot/keyring": ^7.5.1
-    "@polkadot/rpc-provider": 6.4.2-1
-    "@polkadot/types": 6.4.2-1
+    "@polkadot/rpc-provider": 6.4.2
+    "@polkadot/types": 6.4.2
     "@polkadot/util": ^7.5.1
     rxjs: ^7.4.0
   languageName: unknown
   linkType: soft
 
-"@polkadot/rpc-provider@6.4.2-1, @polkadot/rpc-provider@workspace:packages/rpc-provider":
+"@polkadot/rpc-provider@6.4.2, @polkadot/rpc-provider@workspace:packages/rpc-provider":
   version: 0.0.0-use.local
   resolution: "@polkadot/rpc-provider@workspace:packages/rpc-provider"
   dependencies:
     "@babel/runtime": ^7.15.4
     "@polkadot/keyring": ^7.5.1
-    "@polkadot/types": 6.4.2-1
+    "@polkadot/types": 6.4.2
     "@polkadot/util": ^7.5.1
     "@polkadot/util-crypto": ^7.5.1
     "@polkadot/x-fetch": ^7.5.1
@@ -2038,10 +2038,10 @@ __metadata:
     "@babel/core": ^7.15.8
     "@babel/register": ^7.15.3
     "@babel/runtime": ^7.15.4
-    "@polkadot/api": 6.4.2-1
-    "@polkadot/rpc-provider": 6.4.2-1
-    "@polkadot/types": 6.4.2-1
-    "@polkadot/types-support": 6.4.2-1
+    "@polkadot/api": 6.4.2
+    "@polkadot/rpc-provider": 6.4.2
+    "@polkadot/types": 6.4.2
+    "@polkadot/types-support": 6.4.2
     "@polkadot/util": ^7.5.1
     "@types/websocket": ^1.0.4
     "@types/yargs": ^17.0.4
@@ -2057,18 +2057,18 @@ __metadata:
   languageName: unknown
   linkType: soft
 
-"@polkadot/types-known@6.4.2-1, @polkadot/types-known@workspace:packages/types-known":
+"@polkadot/types-known@6.4.2, @polkadot/types-known@workspace:packages/types-known":
   version: 0.0.0-use.local
   resolution: "@polkadot/types-known@workspace:packages/types-known"
   dependencies:
     "@babel/runtime": ^7.15.4
     "@polkadot/networks": ^7.5.1
-    "@polkadot/types": 6.4.2-1
+    "@polkadot/types": 6.4.2
     "@polkadot/util": ^7.5.1
   languageName: unknown
   linkType: soft
 
-"@polkadot/types-support@6.4.2-1, @polkadot/types-support@workspace:packages/types-support":
+"@polkadot/types-support@6.4.2, @polkadot/types-support@workspace:packages/types-support":
   version: 0.0.0-use.local
   resolution: "@polkadot/types-support@workspace:packages/types-support"
   dependencies:
@@ -2077,13 +2077,13 @@ __metadata:
   languageName: unknown
   linkType: soft
 
-"@polkadot/types@6.4.2-1, @polkadot/types@workspace:packages/types":
+"@polkadot/types@6.4.2, @polkadot/types@workspace:packages/types":
   version: 0.0.0-use.local
   resolution: "@polkadot/types@workspace:packages/types"
   dependencies:
     "@babel/runtime": ^7.15.4
     "@polkadot/keyring": ^7.5.1
-    "@polkadot/types-support": 6.4.2-1
+    "@polkadot/types-support": 6.4.2
     "@polkadot/util": ^7.5.1
     "@polkadot/util-crypto": ^7.5.1
     "@types/bn.js": ^4.11.6