Hard Drive

How to Fix External Hard Drive Cyclic Redundancy Error

8 min read

Reading Time: 8 minutesThe external hard drive Cyclic Redundancy error is a cause for concern because it commonly indicates a dying hard drive. Our guide explains how you can retrieve data from your external HDD. And once data recovery is complete, you can try one of the various fixes for the Cyclic Redundancy error listed in this article.

What is a Cyclic Redundancy Check

In simple words, Cyclic Redundancy Check (CRC) is an error-checking mechanism that’s usually implemented in storage drives and networks. It checks the integrity of data during transfer, by using a modified version of the checksum algorithm. To pass the error checks, the CRC checksum values should be identical across the receiving (for example, your computer reading an external hard drive) and the transmitting end (the external hard drive).

CRC contains the term “redundancy” because it increases the data size, without adding any new information, and “cyclical” because of how its math works. The mathematics behind CRC is a little complex, but you can find a relatively straightforward understanding of it on the Cardinal Peak website.

While CRC checks whether the data is intact, it doesn’t fix it. Upon detecting a discrepancy, it typically stops the read/write operation and prompts the computer to perform it again.

CRC was developed back in 1961 and the easy implementation and accuracy of CRC error checking quickly led to its widespread adoption. However, CRC is not without flaws. A major shortcoming of CRC error checking is that while it can check the integrity of a file, it cannot determine its authenticity.

What Causes Data Error (Cyclic Redundancy Check)?

Windows will display the “Data error (Cyclic Redundancy Check)” dialog box if there’s a mismatch between the transmitted and received checksum. If you’re lucky, the error could simply be a case of a malfunctioning SATA/USB cable, or a connection port. More commonly, a failed CRC check indicates a dying or severely corrupted hard drive or USB drive.

The error frequently appears when copying files to and from the hard disk drive. Some users also report seeing the “Data error (Cyclic Redundancy Check)” message when initializing a disk.

Before you proceed to fix the CRC error, here are some common culprits behind the issue:

  • ⚠️ Damaged Ports and Connectors: A damaged USB cable or port is a common reason why your PC displays the “Data error (Cyclic Redundancy Check)” message when you connect your external HDD.
  • 💽 Corrupted External HDD: Bad sectors, viruses, format interruption, power cuts, and improper ejection can all contribute towards a logically corrupted hard drive. This damages the data on your drive and prevents it from being read properly, resulting in the cyclic redundancy error. Signs of a corrupted hard drive include slow performance, disappeared files, and an inaccessible drive.
  • 📕 Registry Errors: In rare cases, corrupted entries in the Windows Registry can cause the CRC error on your external hard drive.
  • ❌ Interrupted Program Installation: If an app’s installation was interrupted, it can result in misconfigured and corrupt program files. Your PC will have trouble reading these files, causing the external hard drive cyclic redundancy error.
  • 🗄️ Incorrect File Configuration: An incorrectly configured file can prompt your PC to display the CRC error when you try to access or copy it. Such files are easy to detect because the error will persist even if you try to copy or access them on other computers. All other files will function like they normally would.
  • 💻 Corrupted Partition: It’s entirely possible that one of the partitions on your external hard drive is logically damaged, and the error appears only when accessing that particular partition.

How To Recover Data After Facing the Cyclic Redundancy Error

Since the CRC error is typically caused by a dying external hard drive, it’s best to recover your data as soon as possible. You may also need to format your external hard drive when attempting to fix the Cyclic Redundancy Check error, making data recovery even more important.

Fortunately, there are plenty of third-party programs that can help you recover your data.

In our data recovery guide, we’ll use Disk Drill because it’s user-friendly and has a high recovery rate. More importantly, it lets you create disk images and scan them for lost data. This will minimize further stress on your already damaged external hard drive. As a bonus, Windows users get to retrieve up to 500 MB of data without paying a penny.

Create a Disk Image Using Disk Drill

  1. Download Disk Drill and run the setup.
  2. Connect the drive facing the Cyclic Redundancy error.
  3. Open Disk Drill and click on the Drive backup option under Extra tools.Drive backup option in Disk Drill.
  4. Select your drive and click Byte-to-byte Backup.The Byte-to-byte backup screen in Disk Drill.
  5. Choose a location for the disk image. It should have free space equal to the entire storage capacity of the external hard drive. Click OK.Byte-to-byte parameters window.
  6. Disk Drill will create the disk image. The process may take a while (enough to fix yourself a cup of coffee).

Scan the Disk Image for Recoverable Data

  1. Open Disk Drill, and ensure you’re on the Storage devices tab.Storage devices tab in Disk Drill.
  2. Click on the Attach disk image option, find the disk image, and click Open. It’ll appear as a storage drive in Disk Drill.Attach disk image option in Disk Drill.
  3. Select the disk image you just added, and click on Search for lost data.Search for lost data option in Disk Drill.
  4. Click Review found items to view the existing as well as recoverable files on the drive. You can directly click on the relevant file type you want to recover (Pictures, Video, Audio, Documents, Archives, and Other).Review found items screen in Disk Drill.
  5. Expand the section you want. For example, if you would like to retrieve the files that are already on the drive, but aren’t accessible due to the CRC error, click on the Existing section. You can also expand the Deleted or lost section to view files that were deleted but are still recoverable.Type of recoverable files in Disk Drill.
  6. Use the checkboxes to select the files you wish to recover. Disk Drill displays a preview of each file you select. After confirming, click on Recover.List of recoverable files in Disk Drill.
  7. Choose a recovery destination for the files and click Next.Recovery destination prompt in Disk Drill.
  8. Disk Drill will recover your files.Data recovery complete screen in Disk Drill.

How To Fix the Cyclic Redundancy Check Error on Your Hard Drive

If your external hard drive is old, showing signs of slow performance, or making clicking/whirring sounds, it’s best to replace it. But, if the “Data error (Cyclic Redundancy Check)” message appeared on an otherwise perfect hard drive, you can fix it at home, using the methods listed below.

Before proceeding to more elaborate fixes, here are some simple things you can do that may fix the CRC error:

  • 📁 Check the File You’re Transferring: To rule out the possibility of an incorrectly configured file, try transferring the file to another drive. If the transfer is successful, the issue lies with your external hard drive, if not, then the file is problematic.
  • 🔌 Check the USB Ports and Cables: Connect your drive to another USB port (preferably one that’s directly attached to your machine’s motherboard), and use different USB cables. If the error persists, the issue lies with your external hard drive and not the cables/ports.

Now let’s take a look at some software-operated methods to fix your external hard drive’s Cyclic Redundancy error:

Method 1: Run CHKDSK

The CHKDSK utility can automatically find and fix numerous logical errors on your hard drive. Here’s how you can use CHKDSK to fix the CRC error on your external hard drive:

  1. Search for cmd in Windows Search (Windows Key + S). Right-click on Command Prompt > Run as administrator.The Command Prompt search result in Windows Search.
  2. In the console, type chkdsk X: /f, and press Enter. Replace X with the drive letter of your external hard drive.CHKDSK Command syntax.
  3. That’s it! CHDSK will scan your drive and automatically fix any errors it detects.

Method 2: Use the SFC Command

System File Checker (SFC) is another diagnostic utility in Windows. It detects and fixes corrupt files on your system. To resolve the Cyclic Redundancy error on your externall hard drive, follow these steps:

  1. Look up CMD in Windows Search and right-click on Command Prompt > Run as administrator.The Command Prompt search result in Windows Search.
  2. In the CMD console, type sfc /scannow and press Enter.The SFC command's syntax.
  3. Wait for Windows to find and fix corrupted system files.

Method 3: Format the Drive

If your external drive has become RAW, it’s best to format it to fix the CRC error. A drive turns RAW when its file system is damaged or is missing entirely. Remember to recover your data first (Disk Drill can detect and recover data from RAW drives).

Here is how to format your external hard drive:

  1. Open Windows Explorer.
  2. Right-click on the drive and choose Format.The Format option in Windows Explorer.
  3. In the Format Options window, leave the Perform a Quick Format option ticked. Click on Start. Windows will format the drive.Format parameters in Windows.

Method 4: Repair the Drive

Physically damaged hard drives should not be handled at home because of how delicate they are, and the high chances of worsening data loss.

If the CRC error is accompanied by clicking and whirring noises from your hard drive, contact a professional data recovery service. In most cases, a good data recovery service should be able to repair your hard drive and get back your data.

Attempting DIY data recovery is not recommended.


The CRC check failed error can be a tricky issue to deal with because it can happen due to a file that’s simply corrupted or something more complicated, like a failing hard drive. Thankfully, even if you have to replace the drive, data recovery programs make it possible for you to retain your previous data. Once the data is secure, you can safely try the fixes listed above and fix the cyclic redundancy error on your external hard drive.