Can't open a file? This frustrating problem has several common causes: you might be missing the required software, the file extension could be wrong, the file might be corrupted, or there could be compatibility issues between the file format and your operating system.

Quick Fix: Right-click the file and select "Open with" to choose a different program. If no suitable program appears, you'll need to install software that supports this file type.

Top 5 Reasons Why Files Won't Open

1. Missing or Wrong Software

The most common reason. Each file type requires specific software to open it. If you don't have the right program installed, your operating system won't know how to display the file.

Examples:

.PSD files need Adobe Photoshop (or GIMP as free alternative)
.DOCX files need Microsoft Word (or LibreOffice, Google Docs)
.AI files need Adobe Illustrator (or Inkscape)
.DWG files need AutoCAD (or DraftSight)
.MP4 files need VLC Player or Windows Media Player

2. Incorrect File Extension

Sometimes files have the wrong extension (the letters after the dot). A JPG image mistakenly renamed as "photo.txt" won't open in image viewers because your computer thinks it's a text file.

How to Fix Wrong Extensions:

Windows:

Open File Explorer
Click View → Show → Check File name extensions
Right-click the file → Rename
Change the extension to the correct one (e.g., from .txt to .jpg)

Mac:

Right-click the file → Get Info
Expand Name & Extension
Uncheck Hide extension
Edit the extension and press Enter

3. File Corruption

Files can become corrupted due to incomplete downloads, storage device errors, malware, or sudden power loss during saving. Corrupted files may refuse to open or display errors.

Signs of corruption:

Error messages like "File is damaged" or "Cannot open file"
File size is 0 KB or unusually small
File opens but displays garbage characters or black screen
Program crashes when trying to open the file

See our detailed guide: Why Does My File Say Corrupted?

4. Unsupported File Format Version

Newer file format versions may not open in older software. For example, a .DOCX file created in Word 2024 might not open in Word 2007.

5. Operating System Restrictions

Some file types are blocked by security policies:

Windows SmartScreen may block files downloaded from the internet
macOS Gatekeeper prevents opening apps from unidentified developers
Linux permissions may prevent execution of scripts or programs

How to Identify Unknown File Types

Method 1: Check the File Extension

The extension (letters after the last dot) tells you what type of file it is. Enable "Show file extensions" in your operating system settings to see them.

Common extensions:

Images: .jpg, .png, .gif, .bmp, .svg, .webp, .heic
Documents: .pdf, .docx, .xlsx, .pptx, .txt, .rtf
Archives: .zip, .rar, .7z, .tar, .gz
Videos: .mp4, .avi, .mkv, .mov, .wmv
Audio: .mp3, .wav, .flac, .aac, .ogg

Method 2: Use Online File Identifier

Upload the file to an online file type checker like:

file.org - Comprehensive file type database
whatext.com - Identifies file types by content
TrID File Identifier - Analyzes file headers

Method 3: Open in Text Editor (Advanced)

Open the file in Notepad (Windows) or TextEdit (Mac) to see the file header. The first few characters often reveal the file type:

%PDF- = PDF file
PK = ZIP archive (also DOCX, XLSX, PPTX)
GIF89a or GIF87a = GIF image
ÿØÿà = JPEG image
<?xml = XML document

Platform-Specific Solutions

Windows 10/11

Fix "Windows cannot open this file" Error:

Right-click the file → Open with → Choose another app
Select an installed program from the list
Check Always use this app to set as default
If no suitable app appears, click Look for another app on this PC
Navigate to C:\Program Files\ to find installed software

Unblock Downloaded Files:

Right-click the file → Properties
At the bottom, check Unblock
Click OK and try opening again

macOS

Bypass "Cannot be opened because the developer cannot be verified":

Go to System Settings → Privacy & Security
Scroll down to find the blocked app
Click Open Anyway
Enter your password to confirm

Alternative Method:

Right-click (or Control-click) the file
Select Open from the menu
Click Open in the warning dialog

Linux

Fix Permission Issues:

If a file won't execute, it may lack execute permissions:

Right-click the file → Properties
Go to Permissions tab
Check Allow executing file as program

Or use terminal:

chmod +x filename

Software Recommendations by File Type

Image Files (.PSD, .AI, .RAW, .HEIC)

Free: GIMP, Paint.NET, IrfanView, XnView
Paid: Adobe Photoshop, Affinity Photo
Online: Photopea (free Photoshop alternative)

Document Files (.DOCX, .XLSX, .PPTX)

Free: LibreOffice, Google Docs/Sheets/Slides, OnlyOffice
Paid: Microsoft Office 365
Viewer only: Microsoft Office Online (free)

Archive Files (.RAR, .7Z, .TAR.GZ)

Windows: 7-Zip (free), WinRAR
Mac: The Unarchiver (free), Keka
Linux: Built-in Archive Manager, p7zip

Video Files (.MKV, .FLV, .AVI)

Free: VLC Media Player (plays everything), MPV
Windows: Windows Media Player (limited formats)
Mac: IINA, QuickTime Player

Audio Files (.FLAC, .APE, .OGG)

Free: VLC, Foobar2000, Audacity
Online: CloudConvert (convert to MP3)

Beware of Fake Software

When searching for software to open files, be careful of malicious websites offering "free codecs" or "file openers." These often install malware. Always download from official sources:

Developer's official website
Microsoft Store / Mac App Store
Reputable download sites (SourceForge, GitHub)

When to Convert Instead of Opening

Sometimes it's easier to convert a file to a more common format rather than installing specialized software:

HEIC → JPG: For iPhone photos that won't open on Windows
WebP → PNG: For web images that won't open in older software
RAR → ZIP: For archives when you can't install WinRAR
FLAC → MP3: For audio files incompatible with your player

Browse our file converters for quick format conversion.

Pro Tip

Install VLC Media Player (free) as a universal file opener. It can open almost any video, audio, and even some image formats. It's available for Windows, Mac, and Linux.