A “cyclic redundancy check” (CRC) error means that the data on your storage device is corrupt and unreadable. The device’s operating system performed a data-verification check and the result didn’t match what was expected, which means that the raw data on the disk is different from when it was last written.
CRC errors can indicate physical issues with a hard drive, solid-state drive (SSD), memory card, or other storage device. The safest course of action is to turn the device off and contact a professional data recovery provider; learn why we discourage the use of data recovery software when treating file corruption.
Below, we’ll provide a detailed definition of cyclic redundancy check errors. If you’ve lost access to important files, we’re here to help: Datarecovery.com provides risk-free evaluations, and with our no data, no charge guarantee, you don’t pay for failed data recovery attempts.
Call 1-800-237-4200 to discuss your case with an expert or schedule a risk-free evaluation online.
Understanding the Cyclic Redundancy Check
A cyclic redundancy check determines whether data is valid. When your computer saves a file, it runs a calculation on the data and generates a short, fixed-length value — the CRC — and stores that data.
When you later access that file, the computer performs the same calculation again. It then compares the new result to the original CRC value stored on the drive.
- If the two values match, the data is considered intact and valid.
- If the two values do not match, the system triggers a CRC error.
When a CRC fails, the data being read is not the same as the data that was written.
Common Causes of CRC Errors
A CRC error can occasionally be a one-off glitch, but it usually points to a more significant problem. The cause of a CRC error is most likely one of the following:
- Storage Device Failure: Hard drives and solid-state drives can develop bad sectors or suffer from firmware corruption. When a part of the drive becomes unreadable or degraded, the data stored there becomes corrupted, leading to a CRC mismatch.
If your drive is making unusual noises (clicking or grinding), this is almost certainly the case — and if your drive is showing those types of physical symptoms, turn it off immediately. You’re probably dealing with a hard drive head crash, and operating the drive risks permanent data loss. - File Transfer Interruption: If you’re copying a large file and the process is interrupted, corruption will occur. The extent of that corruption depends on quite a few factors, but you never want to interrupt a write process.
- Improper System Shutdown: A sudden power loss or forcing a shutdown while the operating system is writing data can corrupt files. In severe cases, it could also damage the file system structure.
- Software or Application Bugs: A poorly written program might corrupt a file when saving it, creating a CRC error the next time you try to open it.
Related content: SSD Firmware Corruption: Causes, Symptoms, and Data Recovery Tips
CRC Errors: What to Do Next
If you encounter a CRC error, your next steps depend on the importance of the data and whether you have backups.
Before attempting any complex fixes, rule out the easiest culprits.
- Re-download or Re-copy the File: If the file came from an external source (like an internet download or another drive), the simplest solution is to get a fresh copy. The original might be fine, and the error may have occurred during the transfer.
- Check Your Connections: If the error involves an external drive, try a different USB port and a different cable.
Build-In Disk Utilities (Hard Drive Only — Not for SSDs)
Operating systems have built-in tools designed to find and repair file system errors. Do not use these tools if you cannot recreate the data — they can cause permanent data loss if used on a failing hard drive.
- For Windows, this tool is Check Disk (often run as chkdsk /r in the Command Prompt).
- For macOS, you can use First Aid within the Disk Utility application.
These utilities will scan the drive for bad sectors and file system inconsistencies and attempt to repair them.
Note: While chkdsk can be effective, running it on a physically failing hard drive can be dangerous. The intensive read/write process can worsen the damage and make professional recovery more difficult or even impossible.
If the data is critical, do not run any software-based repair utilities. The best practice is to avoid using disk utilities unless you’ve made a complete clone of the drive in question; read our guide to cloning hard drives with ddrescue.
Get Professional Assistance
If the simple fixes don’t work and the data is important, stop. Further DIY attempts can cause permanent data loss.
You need professional data recovery if:
- The data is irreplaceable..
- The drive is making any unusual clicking, buzzing, or grinding sounds.
- The drive is not recognized by your computer’s BIOS or Disk Utility.
- You have tried basic troubleshooting without success.
Data Recovery for CRC Errors
A cyclic redundancy check error is a data loss symptom. It’s often one of the first symptoms of storage device failure, so treat it as a serious issue.
At Datarecovery.com, we specialize in recovering data from physically damaged and logically corrupted storage media. Our engineers use proprietary tools in a certified cleanroom environment to safely diagnose and treat storage device failure, ensuring the highest possible chance of a successful recovery.
We offer a risk-free evaluation and stand by our “no data, no charge” guarantee: If we can’t recover the data you need, you don’t pay for the attempt.
If you’re facing CRC errors and can’t afford to lose your files, we can help. Contact us at 1-800-237-4200 or submit a case online for a free evaluation.
