diff --git a/src/classes/errors/delayed-error.ts b/src/classes/errors/delayed-error.ts
index 7e04fad7c2..309805c894 100644
--- a/src/classes/errors/delayed-error.ts
+++ b/src/classes/errors/delayed-error.ts
@@ -1,3 +1,5 @@
+export const DELAYED_ERROR = 'bullmq:movedToDelayed';
+
 /**
  * DelayedError
  *
@@ -6,7 +8,7 @@
  *
  */
 export class DelayedError extends Error {
-  constructor(message?: string) {
+  constructor(message: string = DELAYED_ERROR) {
     super(message);
     this.name = this.constructor.name;
     Object.setPrototypeOf(this, new.target.prototype);
diff --git a/src/classes/errors/unrecoverable-error.ts b/src/classes/errors/unrecoverable-error.ts
index 6a48e04902..e46db6fb68 100644
--- a/src/classes/errors/unrecoverable-error.ts
+++ b/src/classes/errors/unrecoverable-error.ts
@@ -1,3 +1,5 @@
+export const UNRECOVERABLE_ERROR = 'bullmq:unrecoverable';
+
 /**
  * UnrecoverableError
  *
@@ -6,7 +8,7 @@
  *
  */
 export class UnrecoverableError extends Error {
-  constructor(message?: string) {
+  constructor(message: string = UNRECOVERABLE_ERROR) {
     super(message);
     this.name = this.constructor.name;
     Object.setPrototypeOf(this, new.target.prototype);
diff --git a/src/classes/errors/waiting-children-error.ts b/src/classes/errors/waiting-children-error.ts
index a9859fbd59..45877af553 100644
--- a/src/classes/errors/waiting-children-error.ts
+++ b/src/classes/errors/waiting-children-error.ts
@@ -1,3 +1,5 @@
+export const WAITING_CHILDREN_ERROR = 'bullmq:movedToWaitingChildren';
+
 /**
  * WaitingChildrenError
  *
@@ -6,7 +8,7 @@
  *
  */
 export class WaitingChildrenError extends Error {
-  constructor(message?: string) {
+  constructor(message: string = WAITING_CHILDREN_ERROR) {
     super(message);
     this.name = this.constructor.name;
     Object.setPrototypeOf(this, new.target.prototype);
diff --git a/src/classes/job.ts b/src/classes/job.ts
index 531839e62c..ec63e0027b 100644
--- a/src/classes/job.ts
+++ b/src/classes/job.ts
@@ -33,7 +33,7 @@ import {
   invertObject,
 } from '../utils';
 import { Backoffs } from './backoffs';
-import { Scripts, raw2NextJobData } from './scripts';
+import { Scripts } from './scripts';
 import { UnrecoverableError } from './errors/unrecoverable-error';
 import type { QueueEvents } from './queue-events';
 import { SpanKind } from '../enums';
diff --git a/tests/fixtures/fixture_processor_unrecoverable.js b/tests/fixtures/fixture_processor_unrecoverable.js
index 57b39f9233..0fdde7c58b 100644
--- a/tests/fixtures/fixture_processor_unrecoverable.js
+++ b/tests/fixtures/fixture_processor_unrecoverable.js
@@ -13,7 +13,7 @@ module.exports = function (job) {
       throw new Error('Not yet!');
     }
     if (job.attemptsMade < 2) {
-      throw new UnrecoverableError('Unrecoverable');
+      throw new UnrecoverableError();
     }
   });
 };
diff --git a/tests/test_sandboxed_process.ts b/tests/test_sandboxed_process.ts
index c246a06458..0635200ff2 100644
--- a/tests/test_sandboxed_process.ts
+++ b/tests/test_sandboxed_process.ts
@@ -2,7 +2,14 @@ import { expect } from 'chai';
 import { pathToFileURL } from 'url';
 import { default as IORedis } from 'ioredis';
 import { after } from 'lodash';
-import { FlowProducer, Job, Queue, QueueEvents, Worker } from '../src/classes';
+import {
+  FlowProducer,
+  Job,
+  Queue,
+  QueueEvents,
+  UNRECOVERABLE_ERROR,
+  Worker,
+} from '../src/classes';
 import { beforeEach, before, after as afterAll, it } from 'mocha';
 import { v4 } from 'uuid';
 import { delay, removeAllQueueData } from '../src/utils';
@@ -501,7 +508,7 @@ function sandboxProcessTests(
           'test',
           { foo: 'bar' },
           {
-            attempts: 3,
+            attempts: 5,
             backoff: 1000,
           },
         );
@@ -512,7 +519,7 @@ function sandboxProcessTests(
             after(2, (job: Job, error) => {
               const elapse = Date.now() - start;
               expect(error.name).to.be.eql('UnrecoverableError');
-              expect(error.message).to.be.eql('Unrecoverable');
+              expect(error.message).to.be.eql(UNRECOVERABLE_ERROR);
               expect(elapse).to.be.greaterThan(1000);
               expect(job.attemptsMade).to.be.eql(2);
               resolve();