5 Ways to Fix ‘The Archive Is Either in Unknown Format Or Damaged’

Have you ever tried to open a compressed RAR or ZIP archive file and received the error message "the archive is either in unknown format or damaged?" Did you identify the source of the error? What approach did you use to fix it?

This issue frequently occurs while attempting to open or download a zipped or RAR file. Windows File Explorer cannot open zip files, and WinRAR reports that the files are corrupted. But, of course, this isn't the only reason.

Why does the error ‘the archive is either in unknown format or damaged’ occur?

This error usually occurs when there is a problem with the compressed file itself, both ZIP and RAR archives. Firstly, the file may have been corrupted during the compression process due to interruptions in data transfer, e.g. unstable network or sudden system shutdown. These interruptions may cause incomplete or inconsistent data stored in the archive, which the extraction software cannot read.

In some cases, users may inadvertently rename files without realizing that the internal content has not changed. When a file labeled as a ZIP archive may be in a different format or corrupted, an error message will be displayed when trying to open or extract it. These 2 cases are caused by a mismatch between the file extension and the actual format of the archive.

Problems with the compression software itself or with older versions may cause problems, as some software versions may have difficulty recognizing new compression algorithms or handling larger file sizes.

What to do when the archive is either in unknown format or damaged?

Because the archive issue can arise for a variety of causes, there are numerous approaches to addressing it. Once the issue is resolved, you will be able to open your zipped file properly.

Solution 1: Re-download the Zipped or RAR archive file

The error message "the archive is either in unknown format or damaged RAR" might be the consequence of an incomplete file download. Then you must download the compressed or RAR package again.

Now, you may see if the "the archive is either in unknown format or damaged" error has disappeared. If not, the file may be corrupted. You can refer to the following solution.

Solution 2: Check disk errors

If re-downloading the archive file does not resolve the issue, you might look for disk issues on your PC. Sometimes disk corruption results in file corruption. You need to solve the disk problems. There are two solutions to this mistake.

Option 1: Use CHKDSK Utility

You can use the system tool CHKDSK utility to investigate and repair bad sectors in the hard disk to fix this error.

Step 1: Press the Win + S key and type cmd.exe in the search box.

Step 2: When the Command Prompt appears, right-click on it and select Run as administrator.

Step 3: In the Command Prompt window, type the chkdsk c: /f /r /x command. Then press Enter to execute.

Option 2: use AOMEI Partition Assistant Standard

If the previous procedure does not resolve the problem, you can utilize a professional disk management program to diagnose hard disk issues. It is advised that you try the AOMEI Partition Assistant Standard.

On a Windows PC, you can use AOMEI Partition Assistant's Check File System and Surface Test tool to resolve the issue that the archive is either in an unknown format or corrupted. Furthermore, this program allows you to move/resize/merge/extend partitions, wipe drives, and upgrade to bigger disks without losing data, among other things.

Tip: If there is accidental file loss, you can quickly try “Recover Data” to retrieve files back immediately.

Step 1. Free download the software, install and launch it. It will display to you the basic situation of your hard drives. Select the partition that you want to check for, right-click it, select Advanced -> Check Partition.

Step 2. It will pop up a small window that you can select the way of checking errors to perform. Choose one according to your needs and click OK. It will proceed immediately.

Notes: ①There are 3 ways you can select to perform: check partition and fix errors in this partition by using chkdsk.exe; check the partition for errors by using chkdsk.exe; check whether there are bad sectors on the partition. Select the one as your command. ②If the partition you selected is being used by another process, you cannot continue the operation. A window will pop up to tell that you can continue the operation again if this partition is dismounted. But it will make all the running programs invalid. When asked “would you like to force a dismount on this partition”. click Yes, it will execute the task, click No, it will cancel the operation.

Solution 3: Use the repair archive in WinRAR

WinRAR has a repair option for damaged ZIP or RAR files. It automatically detects and patches corrupted files. The time required to correctly scan and resolve a file mistake is mostly determined by its size. The methods below will show you how to resolve archive issues using WinRAR.

Step 1: Launch WinRAR on your PC and navigate to the corrupted zip file using the client's address bar.

Step 2: Select the corrupted zip file and click the Repair icon. Alternatively, open the faulty RAR file by double-clicking it, then navigate to the Tools menu and pick the Repair archive option.

Step 3: The software will ask you where you wish to save the file on your computer. Select the appropriate place and click the OK button.

Step 4: The file editing procedure will begin, which might take some time depending on the size of the file.

Step 5: Click the Close button to close the window, then navigate to the folder containing the modified archive. The file will be titled rebuilt.filename.rar or rebuilt.filename.zip.

Solution 4: Use Windows default decompressor

A compression and decompression function in Windows 10 devices helps you to resolve archive errors. This feature is only available for files in ZIP format.

Step 1: Right-click on the compressed (zipped) folder.

Step 2: Choose Extract All from the context menu.

Step 3: By default, the compressed file will be decompressed in the same location as the compressed folder

Solution 5: Scan virus via Windows Defender Security Center

If you download the zip file/folder from an unauthorized or otherwise unknown domain, it may include a virus or malware, resulting in the "the archive is either in unknown format or damaged" problem. As such, there are chances that the file contains some virus or malware.

Step 1: Type virus in the search box and double-click on the Virus & Threat Protection result.

Step 2: Inside the Windows Defender Security Centre, click on Run a new advanced scan.

Step 3: Select Custom scan from the list of scan options and click on the Scan now button.

Step 4: In the pop-up File Explorer box, choose the affected zip folder and click choose Folder. Then, you will be sent back to the Windows Security interface, where you can click Scan Now to begin scanning the zip folder for viruses.

To sum up

The error ‘the archive is either in unknown format or damaged’ is not a serious problem but it still may cause your data file loss. In this article, we covered the most likely reasons and possible ways to fix this error include re-downloading the files, checking for disk errors using AOMEI Partition Assistant, repairing archives using WinRAR, using Windows default decompressor, or scanning for viruses via Windows Defender Security Center.