diff --git a/CHANGELOG.md b/CHANGELOG.md
index aa1314c57b..3efa354ea5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,30 @@
 # CHANGELOG
 
+## 3.5.1 Jan 18, 2020
+
+Upgrade priority: Low. Recommended for parachain developers.
+
+- **Important** The default for Substrate on the Address types are `MultiAddress`. It is recommended that chains add explicit definitions for `Address` and `LookupSource` in their types, instead of relying on the API-defaults. A future update will swap the API defaults to align with Substrate.
+- **Important** Like the above changes in Substrate, the `AccountInfo` structure has also changed. It is recommended that chain developers explicitly add `AccountInfo: 'AccountInfoWithRefCount'` for the version with `refCount` on and `AccountInfoWithProviders` for the latest Substrate version. As per the above, the API defaults will be changed to align with Substrate.
+
+Contributed:
+
+- Apply correct TypeScript type for `toBigInt()` (Thanks to https://github.com/ianhe8x)
+- Expand type definitions for storage key tuples (Thanks to https://github.com/monitz87)
+- Adjust bounty derive to cater for non-council chains (Thanks to https://github.com/ekowalsk)
+
+Changes:
+
+- Remove recursion in vector/struct U8a stream decoding
+- Availability of staking made optional in session length calcs (era does require it)
+- Updates to parachain types, ensuring it has coverage for all the latest
+- Update all Rococo types to the latest (session keys, session reports, parachain indexes)
+- Update known upgrade checkpoints fo WestEnd
+- Add types of the lottery module in Substrate
+- Add and extend types for the crowdloan module in Polkadot
+- Adjust node-template to default to `MultiAddress` on specVersion >= 100
+
+
 ## 3.4.1 Jan 11, 2020
 
 Upgrade priority: Low. Fixes for parachain types, `.entries()` (with no values) and `event.is(...)` checks, users of these interfaces will have benefit.
diff --git a/package.json b/package.json
index 26f566d34a..2a2cb814da 100644
--- a/package.json
+++ b/package.json
@@ -34,5 +34,5 @@
     "@types/jest": "^26.0.20",
     "copyfiles": "^2.4.1"
   },
-  "version": "3.4.2-18"
+  "version": "3.5.0"
 }
diff --git a/packages/api-contract/package.json b/packages/api-contract/package.json
index 690134a099..0ae5e6487a 100644
--- a/packages/api-contract/package.json
+++ b/packages/api-contract/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/api-contract",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "Interfaces for interacting with contracts and contract ABIs",
   "main": "index.js",
   "module": "index.mjs",
@@ -14,10 +14,10 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/api-contract#readme",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@polkadot/api": "3.4.2-18",
-    "@polkadot/types": "3.4.2-18",
+    "@polkadot/api": "3.5.0",
+    "@polkadot/types": "3.5.0",
     "@polkadot/util": "^5.3.1",
-    "@polkadot/x-rxjs": "3.4.2-18",
+    "@polkadot/x-rxjs": "3.5.0",
     "bn.js": "^4.11.9"
   }
 }
diff --git a/packages/api-derive/package.json b/packages/api-derive/package.json
index 4e285651a8..df74b6b0ac 100644
--- a/packages/api-derive/package.json
+++ b/packages/api-derive/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/api-derive",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "Common functions used across Polkadot, derived from RPC calls and storage queries.",
   "main": "index.js",
   "module": "index.mjs",
@@ -14,16 +14,16 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/api-derive#readme",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@polkadot/api": "3.4.2-18",
-    "@polkadot/rpc-core": "3.4.2-18",
-    "@polkadot/types": "3.4.2-18",
+    "@polkadot/api": "3.5.0",
+    "@polkadot/rpc-core": "3.5.0",
+    "@polkadot/types": "3.5.0",
     "@polkadot/util": "^5.3.1",
     "@polkadot/util-crypto": "^5.3.1",
-    "@polkadot/x-rxjs": "3.4.2-18",
+    "@polkadot/x-rxjs": "3.5.0",
     "bn.js": "^4.11.9"
   },
   "devDependencies": {
     "@polkadot/keyring": "^5.3.1",
-    "@polkadot/rpc-provider": "3.4.2-18"
+    "@polkadot/rpc-provider": "3.5.0"
   }
 }
diff --git a/packages/api/package.json b/packages/api/package.json
index cd3f7834d3..4b7fed84f1 100644
--- a/packages/api/package.json
+++ b/packages/api/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/api",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "Promise and RxJS wrappers around the Polkadot JS RPC",
   "main": "index.js",
   "module": "index.mjs",
@@ -17,16 +17,16 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/api#readme",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@polkadot/api-derive": "3.4.2-18",
+    "@polkadot/api-derive": "3.5.0",
     "@polkadot/keyring": "^5.3.1",
-    "@polkadot/metadata": "3.4.2-18",
-    "@polkadot/rpc-core": "3.4.2-18",
-    "@polkadot/rpc-provider": "3.4.2-18",
-    "@polkadot/types": "3.4.2-18",
-    "@polkadot/types-known": "3.4.2-18",
+    "@polkadot/metadata": "3.5.0",
+    "@polkadot/rpc-core": "3.5.0",
+    "@polkadot/rpc-provider": "3.5.0",
+    "@polkadot/types": "3.5.0",
+    "@polkadot/types-known": "3.5.0",
     "@polkadot/util": "^5.3.1",
     "@polkadot/util-crypto": "^5.3.1",
-    "@polkadot/x-rxjs": "3.4.2-18",
+    "@polkadot/x-rxjs": "3.5.0",
     "bn.js": "^4.11.9",
     "eventemitter3": "^4.0.7"
   }
diff --git a/packages/metadata/package.json b/packages/metadata/package.json
index 3d4e1a752a..af23b5594c 100644
--- a/packages/metadata/package.json
+++ b/packages/metadata/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/metadata",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "Helpers to extract information from runtime metadata",
   "main": "index.js",
   "module": "index.mjs",
@@ -17,8 +17,8 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/type-metadata#readme",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@polkadot/types": "3.4.2-18",
-    "@polkadot/types-known": "3.4.2-18",
+    "@polkadot/types": "3.5.0",
+    "@polkadot/types-known": "3.5.0",
     "@polkadot/util": "^5.3.1",
     "@polkadot/util-crypto": "^5.3.1",
     "bn.js": "^4.11.9"
diff --git a/packages/rpc-core/package.json b/packages/rpc-core/package.json
index 7cc5daf218..d36891cac2 100644
--- a/packages/rpc-core/package.json
+++ b/packages/rpc-core/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/rpc-core",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "A JavaScript wrapper for the Polkadot JsonRPC interface",
   "main": "index.js",
   "module": "index.mjs",
@@ -14,11 +14,11 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/rpc-core#readme",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@polkadot/metadata": "3.4.2-18",
-    "@polkadot/rpc-provider": "3.4.2-18",
-    "@polkadot/types": "3.4.2-18",
+    "@polkadot/metadata": "3.5.0",
+    "@polkadot/rpc-provider": "3.5.0",
+    "@polkadot/types": "3.5.0",
     "@polkadot/util": "^5.3.1",
-    "@polkadot/x-rxjs": "3.4.2-18"
+    "@polkadot/x-rxjs": "3.5.0"
   },
   "devDependencies": {
     "@polkadot/keyring": "^5.3.1"
diff --git a/packages/rpc-provider/package.json b/packages/rpc-provider/package.json
index 4352b73369..a96064a5f8 100644
--- a/packages/rpc-provider/package.json
+++ b/packages/rpc-provider/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/rpc-provider",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "Transport providers for the API",
   "main": "index.js",
   "module": "index.mjs",
@@ -14,7 +14,7 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/rpc-provider#readme",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@polkadot/types": "3.4.2-18",
+    "@polkadot/types": "3.5.0",
     "@polkadot/util": "^5.3.1",
     "@polkadot/util-crypto": "^5.3.1",
     "@polkadot/x-fetch": "^5.3.1",
@@ -24,7 +24,7 @@
   },
   "devDependencies": {
     "@polkadot/keyring": "^5.3.1",
-    "@polkadot/metadata": "3.4.2-18",
+    "@polkadot/metadata": "3.5.0",
     "mock-socket": "^9.0.3",
     "nock": "^13.0.5"
   }
diff --git a/packages/typegen/package.json b/packages/typegen/package.json
index 2de2cebb6d..2269d82374 100644
--- a/packages/typegen/package.json
+++ b/packages/typegen/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/typegen",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "Type generation scripts",
   "main": "index.js",
   "module": "index.mjs",
@@ -23,10 +23,10 @@
     "@babel/core": "^7.12.10",
     "@babel/register": "^7.12.10",
     "@babel/runtime": "^7.12.5",
-    "@polkadot/api": "3.4.2-18",
-    "@polkadot/metadata": "3.4.2-18",
-    "@polkadot/rpc-provider": "3.4.2-18",
-    "@polkadot/types": "3.4.2-18",
+    "@polkadot/api": "3.5.0",
+    "@polkadot/metadata": "3.5.0",
+    "@polkadot/rpc-provider": "3.5.0",
+    "@polkadot/types": "3.5.0",
     "@polkadot/util": "^5.3.1",
     "handlebars": "^4.7.6",
     "websocket": "^1.0.33",
diff --git a/packages/types-known/package.json b/packages/types-known/package.json
index b169311603..febae126ba 100644
--- a/packages/types-known/package.json
+++ b/packages/types-known/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/types-known",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "A JavaScript wrapper for the Polkadot JsonRPC interface",
   "main": "index.js",
   "module": "index.mjs",
@@ -14,7 +14,7 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/types-known#readme",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@polkadot/types": "3.4.2-18",
+    "@polkadot/types": "3.5.0",
     "@polkadot/util": "^5.3.1",
     "bn.js": "^4.11.9"
   },
diff --git a/packages/types/package.json b/packages/types/package.json
index e155131e72..d83a7bd684 100644
--- a/packages/types/package.json
+++ b/packages/types/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/types",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "Implementation of the Parity codec",
   "main": "index.js",
   "module": "index.mjs",
@@ -17,10 +17,10 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/types#readme",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@polkadot/metadata": "3.4.2-18",
+    "@polkadot/metadata": "3.5.0",
     "@polkadot/util": "^5.3.1",
     "@polkadot/util-crypto": "^5.3.1",
-    "@polkadot/x-rxjs": "3.4.2-18",
+    "@polkadot/x-rxjs": "3.5.0",
     "@types/bn.js": "^4.11.6",
     "bn.js": "^4.11.9"
   },
diff --git a/packages/x-rxjs/package.json b/packages/x-rxjs/package.json
index e9c0be985b..4f0d0f471b 100644
--- a/packages/x-rxjs/package.json
+++ b/packages/x-rxjs/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/x-rxjs",
-  "version": "3.4.2-18",
+  "version": "3.5.0",
   "description": "A pass-through interface for RxJs (allowing node + mjs usage)",
   "main": "index.js",
   "sideEffects": false,
diff --git a/yarn.lock b/yarn.lock
index 3cabfb4b9e..1c7ff18fb2 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1622,46 +1622,46 @@ __metadata:
   resolution: "@polkadot/api-contract@workspace:packages/api-contract"
   dependencies:
     "@babel/runtime": ^7.12.5
-    "@polkadot/api": 3.4.2-18
-    "@polkadot/types": 3.4.2-18
+    "@polkadot/api": 3.5.0
+    "@polkadot/types": 3.5.0
     "@polkadot/util": ^5.3.1
-    "@polkadot/x-rxjs": 3.4.2-18
+    "@polkadot/x-rxjs": 3.5.0
     bn.js: ^4.11.9
   languageName: unknown
   linkType: soft
 
-"@polkadot/api-derive@3.4.2-18, @polkadot/api-derive@workspace:packages/api-derive":
+"@polkadot/api-derive@3.5.0, @polkadot/api-derive@workspace:packages/api-derive":
   version: 0.0.0-use.local
   resolution: "@polkadot/api-derive@workspace:packages/api-derive"
   dependencies:
     "@babel/runtime": ^7.12.5
-    "@polkadot/api": 3.4.2-18
+    "@polkadot/api": 3.5.0
     "@polkadot/keyring": ^5.3.1
-    "@polkadot/rpc-core": 3.4.2-18
-    "@polkadot/rpc-provider": 3.4.2-18
-    "@polkadot/types": 3.4.2-18
+    "@polkadot/rpc-core": 3.5.0
+    "@polkadot/rpc-provider": 3.5.0
+    "@polkadot/types": 3.5.0
     "@polkadot/util": ^5.3.1
     "@polkadot/util-crypto": ^5.3.1
-    "@polkadot/x-rxjs": 3.4.2-18
+    "@polkadot/x-rxjs": 3.5.0
     bn.js: ^4.11.9
   languageName: unknown
   linkType: soft
 
-"@polkadot/api@3.4.2-18, @polkadot/api@workspace:packages/api":
+"@polkadot/api@3.5.0, @polkadot/api@workspace:packages/api":
   version: 0.0.0-use.local
   resolution: "@polkadot/api@workspace:packages/api"
   dependencies:
     "@babel/runtime": ^7.12.5
-    "@polkadot/api-derive": 3.4.2-18
+    "@polkadot/api-derive": 3.5.0
     "@polkadot/keyring": ^5.3.1
-    "@polkadot/metadata": 3.4.2-18
-    "@polkadot/rpc-core": 3.4.2-18
-    "@polkadot/rpc-provider": 3.4.2-18
-    "@polkadot/types": 3.4.2-18
-    "@polkadot/types-known": 3.4.2-18
+    "@polkadot/metadata": 3.5.0
+    "@polkadot/rpc-core": 3.5.0
+    "@polkadot/rpc-provider": 3.5.0
+    "@polkadot/types": 3.5.0
+    "@polkadot/types-known": 3.5.0
     "@polkadot/util": ^5.3.1
     "@polkadot/util-crypto": ^5.3.1
-    "@polkadot/x-rxjs": 3.4.2-18
+    "@polkadot/x-rxjs": 3.5.0
     bn.js: ^4.11.9
     eventemitter3: ^4.0.7
   languageName: unknown
@@ -1772,14 +1772,14 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@polkadot/metadata@3.4.2-18, @polkadot/metadata@workspace:packages/metadata":
+"@polkadot/metadata@3.5.0, @polkadot/metadata@workspace:packages/metadata":
   version: 0.0.0-use.local
   resolution: "@polkadot/metadata@workspace:packages/metadata"
   dependencies:
     "@babel/runtime": ^7.12.5
     "@polkadot/keyring": ^5.3.1
-    "@polkadot/types": 3.4.2-18
-    "@polkadot/types-known": 3.4.2-18
+    "@polkadot/types": 3.5.0
+    "@polkadot/types-known": 3.5.0
     "@polkadot/util": ^5.3.1
     "@polkadot/util-crypto": ^5.3.1
     bn.js: ^4.11.9
@@ -1795,28 +1795,28 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@polkadot/rpc-core@3.4.2-18, @polkadot/rpc-core@workspace:packages/rpc-core":
+"@polkadot/rpc-core@3.5.0, @polkadot/rpc-core@workspace:packages/rpc-core":
   version: 0.0.0-use.local
   resolution: "@polkadot/rpc-core@workspace:packages/rpc-core"
   dependencies:
     "@babel/runtime": ^7.12.5
     "@polkadot/keyring": ^5.3.1
-    "@polkadot/metadata": 3.4.2-18
-    "@polkadot/rpc-provider": 3.4.2-18
-    "@polkadot/types": 3.4.2-18
+    "@polkadot/metadata": 3.5.0
+    "@polkadot/rpc-provider": 3.5.0
+    "@polkadot/types": 3.5.0
     "@polkadot/util": ^5.3.1
-    "@polkadot/x-rxjs": 3.4.2-18
+    "@polkadot/x-rxjs": 3.5.0
   languageName: unknown
   linkType: soft
 
-"@polkadot/rpc-provider@3.4.2-18, @polkadot/rpc-provider@workspace:packages/rpc-provider":
+"@polkadot/rpc-provider@3.5.0, @polkadot/rpc-provider@workspace:packages/rpc-provider":
   version: 0.0.0-use.local
   resolution: "@polkadot/rpc-provider@workspace:packages/rpc-provider"
   dependencies:
     "@babel/runtime": ^7.12.5
     "@polkadot/keyring": ^5.3.1
-    "@polkadot/metadata": 3.4.2-18
-    "@polkadot/types": 3.4.2-18
+    "@polkadot/metadata": 3.5.0
+    "@polkadot/types": 3.5.0
     "@polkadot/util": ^5.3.1
     "@polkadot/util-crypto": ^5.3.1
     "@polkadot/x-fetch": ^5.3.1
@@ -1844,10 +1844,10 @@ __metadata:
     "@babel/core": ^7.12.10
     "@babel/register": ^7.12.10
     "@babel/runtime": ^7.12.5
-    "@polkadot/api": 3.4.2-18
-    "@polkadot/metadata": 3.4.2-18
-    "@polkadot/rpc-provider": 3.4.2-18
-    "@polkadot/types": 3.4.2-18
+    "@polkadot/api": 3.5.0
+    "@polkadot/metadata": 3.5.0
+    "@polkadot/rpc-provider": 3.5.0
+    "@polkadot/types": 3.5.0
     "@polkadot/util": ^5.3.1
     "@types/websocket": ^1.0.1
     "@types/yargs": ^15.0.12
@@ -1863,28 +1863,28 @@ __metadata:
   languageName: unknown
   linkType: soft
 
-"@polkadot/types-known@3.4.2-18, @polkadot/types-known@workspace:packages/types-known":
+"@polkadot/types-known@3.5.0, @polkadot/types-known@workspace:packages/types-known":
   version: 0.0.0-use.local
   resolution: "@polkadot/types-known@workspace:packages/types-known"
   dependencies:
     "@babel/runtime": ^7.12.5
-    "@polkadot/types": 3.4.2-18
+    "@polkadot/types": 3.5.0
     "@polkadot/util": ^5.3.1
     "@types/bn.js": ^4.11.6
     bn.js: ^4.11.9
   languageName: unknown
   linkType: soft
 
-"@polkadot/types@3.4.2-18, @polkadot/types@workspace:packages/types":
+"@polkadot/types@3.5.0, @polkadot/types@workspace:packages/types":
   version: 0.0.0-use.local
   resolution: "@polkadot/types@workspace:packages/types"
   dependencies:
     "@babel/runtime": ^7.12.5
     "@polkadot/keyring": ^5.3.1
-    "@polkadot/metadata": 3.4.2-18
+    "@polkadot/metadata": 3.5.0
     "@polkadot/util": ^5.3.1
     "@polkadot/util-crypto": ^5.3.1
-    "@polkadot/x-rxjs": 3.4.2-18
+    "@polkadot/x-rxjs": 3.5.0
     "@types/bn.js": ^4.11.6
     bn.js: ^4.11.9
   languageName: unknown
@@ -1982,7 +1982,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@polkadot/x-rxjs@3.4.2-18, @polkadot/x-rxjs@workspace:packages/x-rxjs":
+"@polkadot/x-rxjs@3.5.0, @polkadot/x-rxjs@workspace:packages/x-rxjs":
   version: 0.0.0-use.local
   resolution: "@polkadot/x-rxjs@workspace:packages/x-rxjs"
   dependencies: