diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4b5d916a3..f82255c64 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [9.5.5]
+### Fixed
+- [#11159](https://github.com/MetaMask/metamask-extension/pull/11159): Fixes crash after entering invalid data in to the Hex Data field when sending a transaction
+
 ## [9.5.4]
 ### Fixed
 - [#11153](https://github.com/MetaMask/metamask-extension/pull/11153): Prevent UI crash when the transaction being retried or canceled is missing.
@@ -2239,7 +2243,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Uncategorized
 - Added the ability to restore accounts from seed words.
 
-[Unreleased]: https://github.com/MetaMask/metamask-extension/compare/v9.5.4...HEAD
+[Unreleased]: https://github.com/MetaMask/metamask-extension/compare/v9.5.5...HEAD
+[9.5.5]: https://github.com/MetaMask/metamask-extension/compare/v9.5.4...v9.5.5
 [9.5.4]: https://github.com/MetaMask/metamask-extension/compare/v9.5.3...v9.5.4
 [9.5.3]: https://github.com/MetaMask/metamask-extension/compare/v9.5.2...v9.5.3
 [9.5.2]: https://github.com/MetaMask/metamask-extension/compare/v9.5.1...v9.5.2
diff --git a/app/manifest/_base.json b/app/manifest/_base.json
index 47cc6a5f9..905172d78 100644
--- a/app/manifest/_base.json
+++ b/app/manifest/_base.json
@@ -71,6 +71,6 @@
     "notifications"
   ],
   "short_name": "__MSG_appName__",
-  "version": "9.5.4",
+  "version": "9.5.5",
   "web_accessible_resources": ["inpage.js", "phishing.html"]
 }
diff --git a/app/scripts/controllers/metametrics.js b/app/scripts/controllers/metametrics.js
index 3d0b622ca..c55a97c85 100644
--- a/app/scripts/controllers/metametrics.js
+++ b/app/scripts/controllers/metametrics.js
@@ -330,7 +330,17 @@ export default class MetaMetricsController {
   async trackEvent(payload, options) {
     // event and category are required fields for all payloads
     if (!payload.event || !payload.category) {
-      throw new Error('Must specify event and category.');
+      throw new Error(
+        `Must specify event and category. Event was: ${
+          payload.event
+        }. Category was: ${payload.category}. Payload keys were: ${Object.keys(
+          payload,
+        )}. ${
+          typeof payload.properties === 'object'
+            ? `Payload property keys were: ${Object.keys(payload.properties)}`
+            : ''
+        }`,
+      );
     }
 
     if (!this.state.participateInMetaMetrics && !options?.isOptIn) {
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index 93faa0b48..f255f5c4b 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -347,6 +347,7 @@ export default class MetamaskController extends EventEmitter {
         if (txReceipt && txReceipt.status === '0x0') {
           this.metaMetricsController.trackEvent(
             {
+              event: 'Tx Status Update: On-Chain Failure',
               category: 'Background',
               properties: {
                 action: 'Transactions',
diff --git a/package.json b/package.json
index 050aa01a5..ead85680f 100644
--- a/package.json
+++ b/package.json
@@ -75,6 +75,7 @@
     "**/xmlhttprequest-ssl": "^1.6.2",
     "3box/ipfs/ipld-zcash/zcash-bitcore-lib/lodash": "^4.17.21",
     "3box/ipfs/ipld-zcash/zcash-bitcore-lib/elliptic": "^6.5.4",
+    "3box/ipfs/libp2p-mdns/multicast-dns/dns-packet": "^5.2.2",
     "3box/**/libp2p-crypto/node-forge": "^0.10.0",
     "3box/**/libp2p-keychain/node-forge": "^0.10.0",
     "analytics-node/axios": "^0.21.1",
diff --git a/shared/modules/buffer-utils.js b/shared/modules/buffer-utils.js
new file mode 100644
index 000000000..38a10b094
--- /dev/null
+++ b/shared/modules/buffer-utils.js
@@ -0,0 +1,16 @@
+import { toBuffer as ethUtilToBuffer, isHexString } from 'ethereumjs-util';
+
+/**
+ * Returns a buffer from the provided input, via ethereumjs-util.toBuffer but
+ * additionally handling non hex strings. This is a failsafe as in most cases
+ * we should be primarily dealing with hex prefixed strings with this utility
+ * but we do not want to break the extension for users.
+ * @param {import('ethereumjs-util').ToBufferInputTypes | string} input
+ * @returns {Buffer}
+ */
+export function toBuffer(input) {
+  if (typeof input === 'string' && isHexString(input) === false) {
+    return Buffer.from(input);
+  }
+  return ethUtilToBuffer(input);
+}
diff --git a/shared/modules/buffer-utils.test.js b/shared/modules/buffer-utils.test.js
new file mode 100644
index 000000000..2f5290cca
--- /dev/null
+++ b/shared/modules/buffer-utils.test.js
@@ -0,0 +1,69 @@
+import { strict as assert } from 'assert';
+import BN from 'bn.js';
+import { toBuffer } from './buffer-utils';
+
+describe('buffer utils', function () {
+  describe('toBuffer', function () {
+    it('should work with prefixed hex strings', function () {
+      const result = toBuffer('0xe');
+      assert.equal(result.length, 1);
+    });
+
+    it('should work with non prefixed hex strings', function () {
+      const result = toBuffer('e');
+      assert.equal(result.length, 1);
+    });
+
+    it('should work with weirdly 0x prefixed non-hex strings', function () {
+      const result = toBuffer('0xtest');
+      assert.equal(result.length, 6);
+    });
+
+    it('should work with regular strings', function () {
+      const result = toBuffer('test');
+      assert.equal(result.length, 4);
+    });
+
+    it('should work with BN', function () {
+      const result = toBuffer(new BN(100));
+      assert.equal(result.length, 1);
+    });
+
+    it('should work with Buffer', function () {
+      const result = toBuffer(Buffer.from('test'));
+      assert.equal(result.length, 4);
+    });
+
+    it('should work with a number', function () {
+      const result = toBuffer(100);
+      assert.equal(result.length, 1);
+    });
+
+    it('should work with null or undefined', function () {
+      const result = toBuffer(null);
+      const result2 = toBuffer(undefined);
+      assert.equal(result.length, 0);
+      assert.equal(result2.length, 0);
+    });
+
+    it('should work with UInt8Array', function () {
+      const uint8 = new Uint8Array(2);
+      const result = toBuffer(uint8);
+      assert.equal(result.length, 2);
+    });
+
+    it('should work with objects that have a toBuffer property', function () {
+      const result = toBuffer({
+        toBuffer: () => Buffer.from('hi'),
+      });
+      assert.equal(result.length, 2);
+    });
+
+    it('should work with objects that have a toArray property', function () {
+      const result = toBuffer({
+        toArray: () => ['hi'],
+      });
+      assert.equal(result.length, 1);
+    });
+  });
+});
diff --git a/ui/app/pages/confirm-deploy-contract/confirm-deploy-contract.component.js b/ui/app/pages/confirm-deploy-contract/confirm-deploy-contract.component.js
index 0c37ca083..231cd484a 100644
--- a/ui/app/pages/confirm-deploy-contract/confirm-deploy-contract.component.js
+++ b/ui/app/pages/confirm-deploy-contract/confirm-deploy-contract.component.js
@@ -1,7 +1,7 @@
 import React, { Component } from 'react';
 import PropTypes from 'prop-types';
-import { toBuffer } from 'ethereumjs-util';
 import ConfirmTransactionBase from '../confirm-transaction-base';
+import { toBuffer } from '../../../../shared/modules/buffer-utils';
 
 export default class ConfirmDeployContract extends Component {
   static contextTypes = {
diff --git a/ui/app/pages/confirm-transaction-base/confirm-transaction-base.component.js b/ui/app/pages/confirm-transaction-base/confirm-transaction-base.component.js
index 54646ac64..e20efc83a 100644
--- a/ui/app/pages/confirm-transaction-base/confirm-transaction-base.component.js
+++ b/ui/app/pages/confirm-transaction-base/confirm-transaction-base.component.js
@@ -1,4 +1,3 @@
-import { toBuffer } from 'ethereumjs-util';
 import React, { Component } from 'react';
 import PropTypes from 'prop-types';
 import { ENVIRONMENT_TYPE_NOTIFICATION } from '../../../../shared/constants/app';
@@ -23,6 +22,7 @@ import {
   TRANSACTION_STATUSES,
 } from '../../../../shared/constants/transaction';
 import { getTransactionTypeTitle } from '../../helpers/utils/transactions.util';
+import { toBuffer } from '../../../../shared/modules/buffer-utils';
 
 export default class ConfirmTransactionBase extends Component {
   static contextTypes = {
diff --git a/yarn.lock b/yarn.lock
index 4b05e3819..c40f5432a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -9267,13 +9267,12 @@ dnd-core@^7.4.4:
     invariant "^2.2.4"
     redux "^4.0.1"
 
-dns-packet@^4.0.0:
-  version "4.2.0"
-  resolved "https://registry.yarnpkg.com/dns-packet/-/dns-packet-4.2.0.tgz#3fd6f5ff5a4ec3194ed0b15312693ffe8776b343"
-  integrity sha512-bn1AKpfkFbm0MIioOMHZ5qJzl2uypdBwI4nYNsqvhjsegBhcKJUlCrMPWLx6JEezRjxZmxhtIz/FkBEur2l8Cw==
+dns-packet@^4.0.0, dns-packet@^5.2.2:
+  version "5.2.2"
+  resolved "https://registry.yarnpkg.com/dns-packet/-/dns-packet-5.2.2.tgz#e4c7d12974cc320b0c0d4b9bbbf68ac151cfe81e"
+  integrity sha512-sQN+vLwC3PvOXiCH/oHcdzML2opFeIdVh8gjjMZrM45n4dR80QF6o3AzInQy6F9Eoc0VJYog4JpQTilt4RFLYQ==
   dependencies:
     ip "^1.1.5"
-    safe-buffer "^5.1.1"
 
 doctrine@1.5.0:
   version "1.5.0"