diff --git a/package.json b/package.json
index 0704b80cc..639d296ba 100644
--- a/package.json
+++ b/package.json
@@ -8,9 +8,10 @@
     "test:integration-build": "yarn test:integration-prepare && yarn test:integration-pretty",
     "test:integration-prepare": "ts-node --project packages/tsconfig.settings.json ./scripts/prepare-integration-tests.ts",
     "test:integration-pretty":"prettier --write __tests__/shared/documentationExamples.ts",
-    "test:integration": "yarn test:integration-build && yarn test",
-    "test": "jest --config=jest.json --maxWorkers=2",
-    "test:watch": "jest --config=jest.json --watch --verbose --coverage=false",
+    "test:integration": "yarn test:integration-build && yarn test:ci",
+    "test:ci": "jest --config=jest.json --maxWorkers=2",
+    "test": "jest --config=jest.json --coverage=false",
+    "test:watch": "yarn test --watch --verbose",
     "daf": "./packages/daf-cli/bin/daf.js",
     "prettier": "prettier --write '{packages,__tests__, !build}/**/*.ts'",
     "build-clean": "rimraf ./packages/*/build ./packages/*/node_modules ./packages/*/tsconfig.tsbuildinfo && jest --clearCache",
diff --git a/packages/daf-core/api/daf-core.api.md b/packages/daf-core/api/daf-core.api.md
index 85814b1ab..4650fe69c 100644
--- a/packages/daf-core/api/daf-core.api.md
+++ b/packages/daf-core/api/daf-core.api.md
@@ -16,6 +16,12 @@ export class Agent implements IAgent {
     readonly methods: IPluginMethodMap;
     }
 
+// @public
+export const CoreEvents: {
+    error: string;
+    warning: string;
+};
+
 // @public
 export function createAgent<T extends IPluginMethodMap>(options: IAgentOptions): TAgent<T>;
 
diff --git a/packages/daf-core/src/__tests__/agent.subscriber.test.ts b/packages/daf-core/src/__tests__/agent.subscriber.test.ts
index 66ff14a76..3c87d1d12 100644
--- a/packages/daf-core/src/__tests__/agent.subscriber.test.ts
+++ b/packages/daf-core/src/__tests__/agent.subscriber.test.ts
@@ -1,4 +1,5 @@
 import { Agent } from '../agent'
+import { CoreEvents } from '../coreEvents'
 import { IEventListener } from '../types/IAgent'
 
 function sleep(ms: number) {
@@ -77,7 +78,7 @@ describe('daf-core agent', () => {
       },
     }
     const errorHandler: IEventListener = {
-      eventTypes: ['error'],
+      eventTypes: [CoreEvents.error],
       onEvent: jest.fn(),
     }
     const agent = new Agent({
@@ -88,7 +89,7 @@ describe('daf-core agent', () => {
 
     expect(errorHandler.onEvent).toBeCalledWith(
       {
-        type: 'error',
+        type: CoreEvents.error,
         data: new Error("I can't handle it!!!!"),
       },
       { agent: agent },
@@ -105,9 +106,9 @@ describe('daf-core agent', () => {
       },
     }
     const errorHandler: IEventListener = {
-      eventTypes: ['error'],
+      eventTypes: [CoreEvents.error],
       onEvent: async ({ type, data }, context) => {
-        expect(type).toBe('error')
+        expect(type).toBe(CoreEvents.error)
         const err = data as Error
         expect(err.message).toMatch("I can't handle it after waiting so long!!!!")
       },
@@ -176,7 +177,7 @@ describe('daf-core agent', () => {
       },
     }
     const errorHandler: IEventListener = {
-      eventTypes: ['error'],
+      eventTypes: [CoreEvents.error],
       onEvent: async () => {
         throw new Error('barError')
       },
diff --git a/packages/daf-core/src/agent.ts b/packages/daf-core/src/agent.ts
index a5c9e9061..20065bb37 100644
--- a/packages/daf-core/src/agent.ts
+++ b/packages/daf-core/src/agent.ts
@@ -3,6 +3,7 @@ import { validateArguments, validateReturnType } from './validator'
 import ValidationErrorSchema from './schemas/ValidationError'
 import Debug from 'debug'
 import { EventEmitter } from 'events'
+import { CoreEvents } from './coreEvents'
 
 /**
  * Filters unauthorized methods. By default all methods are authorized
@@ -146,8 +147,8 @@ export class Agent implements IAgent {
               )
               this.eventQueue.push(promise)
               promise?.catch((rejection) => {
-                if (eventType !== 'error') {
-                  this.eventBus.emit('error', rejection)
+                if (eventType !== CoreEvents.error) {
+                  this.eventBus.emit(CoreEvents.error, rejection)
                 } else {
                   this.eventQueue.push(
                     Promise.reject(
@@ -254,10 +255,10 @@ export class Agent implements IAgent {
    * Ex: `await agent.emit('foo', {eventData})`
    *
    * In case an error is thrown while processing an event, the error is re-emitted as an event
-   * of type `error` with a `EventListenerError` as payload.
+   * of type `CoreEvents.error` with a `EventListenerError` as payload.
    *
    * Note that `await agent.emit()` will NOT throw an error. To process errors, use a listener
-   * with `eventTypes: ["error"]` in the definition.
+   * with `eventTypes: [ CoreEvents.error ]` in the definition.
    *
    * @param eventType - the type of event being emitted
    * @param data - event payload.
diff --git a/packages/daf-core/src/coreEvents.ts b/packages/daf-core/src/coreEvents.ts
new file mode 100644
index 000000000..0be8330e7
--- /dev/null
+++ b/packages/daf-core/src/coreEvents.ts
@@ -0,0 +1,20 @@
+/**
+ * This collection defines the core event types.
+ *
+ * @public
+ */
+export const CoreEvents = {
+  /**
+   * This event type is used to signal an error to event listeners.
+   *
+   * @public
+   */
+  error: 'ev_err',
+
+  /**
+   * This event type is used to signal a warning to event listeners.
+   *
+   * @public
+   */
+  warning: 'ev_warn',
+}
diff --git a/packages/daf-core/src/index.ts b/packages/daf-core/src/index.ts
index 793126de0..dbe3e5905 100644
--- a/packages/daf-core/src/index.ts
+++ b/packages/daf-core/src/index.ts
@@ -5,6 +5,7 @@
  */
 export { Agent, createAgent, IAgentOptions } from './agent'
 export { ValidationError } from './validator'
+export { CoreEvents } from './coreEvents'
 export * from './types/IAgent'
 export * from './types/IDataStore'
 export * from './types/IIdentity'
diff --git a/packages/daf-did-comm/src/action-handler.ts b/packages/daf-did-comm/src/action-handler.ts
index 7ea6a0969..da5b2df27 100644
--- a/packages/daf-did-comm/src/action-handler.ts
+++ b/packages/daf-did-comm/src/action-handler.ts
@@ -126,13 +126,13 @@ export class DIDComm implements IAgentPlugin {
           })
         }
 
-        return Promise.reject('Message not sent')
+        return Promise.reject(new Error('Message not sent'))
       } catch (e) {
         return Promise.reject(e)
       }
     } else {
       debug('No Messaging service in didDoc')
-      return Promise.reject('No service endpoint')
+      return Promise.reject(new Error('No service endpoint'))
     }
   }
 }
diff --git a/packages/daf-did-jwt/src/__tests__/message-handler.test.ts b/packages/daf-did-jwt/src/__tests__/message-handler.test.ts
index b3ca2ac36..bd9f258c5 100644
--- a/packages/daf-did-jwt/src/__tests__/message-handler.test.ts
+++ b/packages/daf-did-jwt/src/__tests__/message-handler.test.ts
@@ -87,12 +87,12 @@ describe('daf-did-jwt', () => {
   it('should reject unknown message type', async () => {
     const mockNextHandler = {
       setNext: jest.fn(),
-      handle: jest.fn().mockRejectedValue('Unsupported message type'),
+      handle: jest.fn().mockRejectedValue(new Error('Unsupported message type')),
     }
     const handler = new JwtMessageHandler()
     handler.setNext(mockNextHandler)
     const message = new Message({ raw: 'test', metaData: [{ type: 'test' }] })
-    expect(handler.handle(message, context)).rejects.toEqual('Unsupported message type')
+    await expect(handler.handle(message, context)).rejects.toThrow('Unsupported message type')
   })
 
   it('should set data field for VC jwt', async () => {
diff --git a/packages/daf-elem-did/src/identity-provider.ts b/packages/daf-elem-did/src/identity-provider.ts
index 50fa1917b..28d7c24e8 100644
--- a/packages/daf-elem-did/src/identity-provider.ts
+++ b/packages/daf-elem-did/src/identity-provider.ts
@@ -56,7 +56,7 @@ export class ElemIdentityProvider extends AbstractIdentityProvider {
     })
 
     if (response.status !== 200) {
-      return Promise.reject(response.statusText)
+      return Promise.reject(new Error(response.statusText))
     }
 
     const identity: Omit<IIdentity, 'provider'> = {
@@ -82,7 +82,7 @@ export class ElemIdentityProvider extends AbstractIdentityProvider {
     context: IContext,
   ): Promise<any> {
     if (!identity.controllerKeyId) throw Error('ControllerKeyId does not exist')
-    
+
     const primaryKey = await await context.agent.keyManagerGetKey({ kid: identity.controllerKeyId })
 
     debug('Fetching list of previous operations')
@@ -91,7 +91,7 @@ export class ElemIdentityProvider extends AbstractIdentityProvider {
 
     debug('Operations count:', operations.length)
     if (operations.length === 0) {
-      return Promise.reject('There should be at least one operation')
+      return Promise.reject(new Error('There should be at least one operation'))
     }
 
     const lastOperation = operations.pop()
@@ -120,7 +120,7 @@ export class ElemIdentityProvider extends AbstractIdentityProvider {
 
     if (response2.status !== 200) {
       debug(response2.statusText)
-      return Promise.reject(response2.statusText)
+      return Promise.reject(new Error(response2.statusText))
     }
 
     debug('Success. New publicKey:', key.publicKeyHex)
diff --git a/packages/daf-message-handler/src/__tests__/default.test.ts b/packages/daf-message-handler/src/__tests__/default.test.ts
index c4cdd5f70..0b0ff6dc9 100644
--- a/packages/daf-message-handler/src/__tests__/default.test.ts
+++ b/packages/daf-message-handler/src/__tests__/default.test.ts
@@ -1,6 +1,34 @@
+import { createAgent, IAgentContext, IMessageHandler } from 'daf-core/src'
+import { MessageHandler } from '..'
+import { AbstractMessageHandler, Message } from '../../build'
+
+jest.setTimeout(30000)
+
+class DummyHandler extends AbstractMessageHandler {
+  async handle(message: Message, context: IAgentContext<{}>): Promise<Message> {
+    return super.handle(message, context)
+  }
+}
+
 describe('daf-message-handler', () => {
   const a = 100
   it('should run a dummy test', () => {
     expect(a).toEqual(100)
   })
+
+  let agent = createAgent<IMessageHandler>({
+    plugins: [
+      new MessageHandler({
+        messageHandlers: [new DummyHandler()],
+      }),
+    ],
+  })
+
+  it('should reject unknown message', async () => {
+    expect.assertions(1)
+    const raw = 'some message of unknown format'
+    await expect(agent.handleMessage({ raw, save: false, metaData: [{ type: 'test' }] })).rejects.toThrow(
+      'Unsupported message type',
+    )
+  })
 })
diff --git a/packages/daf-message-handler/src/abstract-message-handler.ts b/packages/daf-message-handler/src/abstract-message-handler.ts
index 4a68a6e4b..3e042fb7c 100644
--- a/packages/daf-message-handler/src/abstract-message-handler.ts
+++ b/packages/daf-message-handler/src/abstract-message-handler.ts
@@ -1,7 +1,7 @@
 import { IAgentContext } from 'daf-core'
 import { Message } from './message'
 
-export const unsupportedMessageTypeError = 'Unsupported message type'
+export const unsupportedMessageTypeError = new Error('Unsupported message type')
 
 /**
  * An abstract class for creating {@link daf-message-handler#MessageHandler} plugins
diff --git a/packages/daf-message-handler/src/message-handler.ts b/packages/daf-message-handler/src/message-handler.ts
index a195d2822..e96016bdf 100644
--- a/packages/daf-message-handler/src/message-handler.ts
+++ b/packages/daf-message-handler/src/message-handler.ts
@@ -5,6 +5,7 @@ import {
   IMessageHandler,
   IHandleMessageArgs,
   schema,
+  CoreEvents,
 } from 'daf-core'
 import { Message } from './message'
 import { AbstractMessageHandler } from './abstract-message-handler'
@@ -15,7 +16,7 @@ const debug = Debug('daf:message-handler')
 export const EventTypes = {
   validatedMessage: 'validatedMessage',
   savedMessage: 'savedMessage',
-  error: 'error',
+  error: CoreEvents.error,
 }
 
 /**
@@ -54,7 +55,7 @@ export class MessageHandler implements IAgentPlugin {
     const { raw, metaData, save } = args
     debug('%o', { raw, metaData, save })
     if (!this.messageHandler) {
-      return Promise.reject('Message handler not provided')
+      return Promise.reject(new Error('Message handler not provided'))
     }
 
     try {
diff --git a/packages/daf-resolver/src/universal-resolver.ts b/packages/daf-resolver/src/universal-resolver.ts
index 23beb1f4e..b4bdd3a07 100644
--- a/packages/daf-resolver/src/universal-resolver.ts
+++ b/packages/daf-resolver/src/universal-resolver.ts
@@ -16,10 +16,10 @@ export class UniversalResolver {
         const ddo = await result.json()
         return ddo.didDocument
       } catch (e) {
-        return Promise.reject(e.message)
+        return Promise.reject(e)
       }
-    } 
-    
+    }
+
     return resolve
   }
-}
\ No newline at end of file
+}
diff --git a/packages/daf-typeorm/api/daf-typeorm.api.md b/packages/daf-typeorm/api/daf-typeorm.api.md
index 3099b6168..4e331ae95 100644
--- a/packages/daf-typeorm/api/daf-typeorm.api.md
+++ b/packages/daf-typeorm/api/daf-typeorm.api.md
@@ -135,7 +135,7 @@ export class DataStoreORM implements IAgentPlugin {
 }
 
 // @public (undocumented)
-export const Entities: (typeof Credential_2 | typeof Identity | typeof Claim | typeof Presentation | typeof Message | typeof Key | typeof Service)[];
+export const Entities: (typeof Identity | typeof Message | typeof Claim | typeof Credential_2 | typeof Presentation | typeof Key | typeof Service)[];
 
 // @public (undocumented)
 export interface FindArgs<TColumns> {
diff --git a/packages/daf-url/src/__tests__/message-handler.test.ts b/packages/daf-url/src/__tests__/message-handler.test.ts
index ea1802e3b..c7a46d22f 100644
--- a/packages/daf-url/src/__tests__/message-handler.test.ts
+++ b/packages/daf-url/src/__tests__/message-handler.test.ts
@@ -18,7 +18,7 @@ describe('daf-url', () => {
 
   it('should reject unknown message type', async () => {
     const message = new Message({ raw: 'test', metaData: [{ type: 'test' }] })
-    expect(messageHandler.handle(message, context)).rejects.toEqual('Unsupported message type')
+    await expect(messageHandler.handle(message, context)).rejects.toThrow('Unsupported message type')
   })
 
   it('should transform message after standard URL', async () => {
@@ -32,7 +32,7 @@ describe('daf-url', () => {
         },
       ],
     })
-    expect(messageHandler.handle(message, context)).rejects.toEqual('Unsupported message type')
+    await expect(messageHandler.handle(message, context)).rejects.toThrow('Unsupported message type')
     expect(message.raw).toEqual(JWT)
   })
 
@@ -40,11 +40,8 @@ describe('daf-url', () => {
     const message = new Message({ raw: 'https://example.com/public-profile.jwt' })
     fetchMock.mockResponse('mockbody')
     expect.assertions(2)
-    try {
-      await messageHandler.handle(message, context)
-    } catch (e) {
-      expect(e).toMatch('Unsupported message type')
-    }
+
+    await expect(messageHandler.handle(message, context)).rejects.toThrow('Unsupported message type')
 
     expect(message.raw).toEqual('mockbody')
   })
diff --git a/packages/daf-w3c/src/__tests__/message-handler.test.ts b/packages/daf-w3c/src/__tests__/message-handler.test.ts
index 55c3de74d..ade9d01cc 100644
--- a/packages/daf-w3c/src/__tests__/message-handler.test.ts
+++ b/packages/daf-w3c/src/__tests__/message-handler.test.ts
@@ -90,7 +90,7 @@ describe('daf-w3c', () => {
 
   it('should reject unknown message type', async () => {
     const message = new Message({ raw: 'test', metaData: [{ type: 'test' }] })
-    expect(handler.handle(message, context)).rejects.toEqual('Unsupported message type')
+    await expect(handler.handle(message, context)).rejects.toThrow('Unsupported message type')
   })
 
   it('should return handled VC message', async () => {