A cyclic redundancy check (CRC) is an error message that appears on the computer screen whenever your PC reads corrupt data. A CRC, basically detects an error in the file that is being read by your PC. This error message commonly occurs when your PC attempts to read data from a damaged storage media, such as a hard disk, CD, or DVD. When data is being transferred to the PC, CRC ensures that data with numerous errors does not reach the specified destination. This is the reason why a corrupted CD does not get copied onto your computer.
Fixing CRC Error
Issues With External Storage Media CD/DVD
Many times, accumulation of dirt on the CD or DVD causes a CRC error. Cleaning this storage media using a soft cloth often solves the problem. A scratched CD or paper labels on the disk can also be an issue. This is because scratches or labels do not allow the disk to burn properly. Partially burnt CDs are especially responsible for causing this error. For extracting information from damaged disks, there are software applications useful in this regard. These are tools that recover data such as lost digital images from corrupted CDs and DVDs.
If the CRC error is still displayed even after running a cleaned disk, then most probably the problem is with the hardware. You need to check your CD and DVD drives and clean them regularly using a lens cleaner disk. Find out whether these devices are functioning properly. Replacing the CD/DVD reader with a new one might solve the problem.
- Incomplete downloads
- System crash
- Buggy software (applications with plenty of bugs)
In such cases, the system may display messages like ‘An invalid Windows file’ or ‘an invalid win32 application’. But it is actually a CRC error.
A file that is not properly downloaded from the Web or an interrupted file transfer can also lead to CRC errors. So before you open the file, check whether it has been downloaded completely. You can use a download manager while downloading any file from the Web. A download manager application keeps a track on the downloading process and informs you when it is complete. Or else, you can again attempt to download from the start and check whether it still occurs.
Defective connections between the computer and the hard drive causes the CRC message to pop up on the screen. For fixing CRC errors related to networking issues, you need to verify all the connections to decode the problem. Sometimes, the connection of a DVD/CD drive is loose that may interfere with the functioning of the devices.
Issues With the Hard Disk
On many occasions, the CRC message is displayed on the screen when the destination (hard drive) has a bad sector. So, even though the DVD/CD is perfectly alright, one may still encounter this error. This happens because the location (hard disk) where you are trying to store the file has a bad sector.
To check whether the location has a bad sector, execute the NUL command on the run command prompt. This command actually reads the content of the file stored on the CD/DVD. For instance, if the DVD drive on your computer is E, and the file nicks.txt in the DVD is stored under the folder tng\audio then the command prompt will look as follows:
E:\tng\audio>xcopy nicks.txt NUL
1 File(s) copied
Because the destination is not specified, it only reads the file. If the command runs successfully, you will get the outcome as 1 file(s) copied, meaning the file has been read successfully and as such there is no issue with it. This indicates that the hard disk is corrupted due to a bad sector. In such case, the solution is to either change the hard disk or burn the DVD on a different machine altogether.
Repairing the Hard Disk
If you are thinking of repairing the hard disk, you can run hard disk recovery programs such as SpinRite. This software program does two things. Firstly, it retrieves data from a bad sector. Secondly, it marks all the bad sector so that data is never written on it in the future. Another option to remove errors from the hard disk is to execute CHKDSK command. This is a check disk command that identifies the bad sectors and tries to restore readable information.
Running CHKDSK from Graphical User Interface (GUI)
Double click the desktop computer icon. Select the partition of your hard drive that you want to scan. As we all know, letters are often used to name disk partitions. Depending upon the size of your hard disk, it will have two or more partitions. So, if your hard disk has 4 partitions, you will have to run the CHKDSK command on each partition to scan the entire hard disk.
Say, you have chosen the D partition (referred to as the D disk drive) of your hard disk. Right click the D disk drive icon and choose the ‘Properties’ option.
The properties window will pop up on your computer screen. Click on the Tools tab to view the ‘Check Now’ button.
Click the ‘Check Now’ button.
The check disk window has two checkboxes ‘Automatically fix file system errors’ and ‘Scan for and attempt recovery of bad sectors’. Check-mark both the boxes and click the ‘Start’ button to ensure that errors that occur while scanning are corrected immediately and data from a bad sector is recovered.
The ‘C’ partition of the hard disk usually contains the operating system files that are running in the background when the computer is in operation. So, if you decide to run the CHKDSK command on the C disk drive, the scanning is unlikely to start. In fact, you will notice a pop-up window that conveys the message “Windows can’t check this disk while it’s in use”. This window pops up if you have installed Windows Vista operating system. The pop up window also has a “Schedule disk check” button. Click on this button and the disk check will be scheduled after you reboot the computer. In other words, you need to switch off the computer properly and start it again to run the CHKDSK command.
Running CHKDSK from the Command Prompt (CMD)
In order to see the command prompt screen, firstly click the Windows ‘Start’ button. Now, type ‘cmd’ in the ‘Start Search’ text box and hit ‘Enter’ button on your keyboard. You will view the command-line utility. The syntax of CHKDSK command is chkdsk drive: /f /r
For searching and recovering data from bad sectors and correcting other errors on the ‘C’ drive of hard disk, type ‘chkdsk c:/r’ in the command prompt and hit the Enter button. For running the CHKDSK command on other partitions of the disk, substitute ‘c’ with the letter that denotes the partition of your disk.
However, if you are not interested in restoring data from the bad sectors and only want to fix errors, then type ‘chkdsk c:/f’. This command completely skips the bad sector while scanning the disk.
How Long to Wait for CHKDSK /r Operation to Complete?
This will depend on the size of your hard disk and the amount of corrupted data. The bigger the hard drive, the longer will be the duration of scan. For instance, a CHKDSK command that is run on a 120 GB capacity hard drive will take around 10 hours to complete. On the other hand, 1 terabyte capacity hard drive full of data may require 30-35 hours to finish the CHKDSK command.
Data Recovery From Corrupted Storage
As aforementioned, popping up of the CRC error when copying a file from an external storage media to the computer (hard drive) is pointing that the CD/DVD has a bad sector. Now, the solution is to retrieve data from the external media storage. For this, you need to go to the command prompt. Use the cd command to change the current working directory to the location where the file is stored. Let’s say user\public is the folder in your CD/DVD (which is on E drive) from where the file is to be copied.
E:\>cd File Location
The command prompt upon execution looks like E:\user\public> indicating our current working directory is user\public.
Suppose nicks.txt is name of the file in which the data is stored. This file is stored in the location (user/public). Now, we have to transfer data from nicks.txt to another new location (say B:\newfolder). For this you need to use the xcopy command that allow you to copy one or more files from one folder to another.
The syntax is as follows: xcopy source destination
xcopy /c nicks.txt B:\newfolder
So, now the command prompt that will allow to copy data will look like this-> E:\user\public> xcopy /c nicks.txt B:\newfolder
There is a high probability that xcopy command may stop copying files as soon as it reads errors from the source (user/public). To avoid such a situation the “/c” option is also used. It ensures that the xcopy command copies data uninterruptedly from the source.
In case, you want to create a copy all files in the folder user\public then instead of nicks.txt, you need to type *.*.
So, the xcopy command will look like xcopy /c *.* B:\newfolder.
Another option is to directly copy all the content from DVD/CD to a new folder in your computer. The syntax is as follows: xcopy /c E:\files C:\files /s /i
Here the data from the files folder in your E drive (which is the CD/DVD drive of your computer) is copied to a new folder /i called files and is located on the C drive. The ‘/s’ option helps to copy all the subdirectories located in E:\files.