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How to open .BAK files on Windows

To open .BAK files on Windows, check the filename and folder for clues, such as .dwg.bak, .txt.bak, a SQL Server backup folder, or an application-specific backup directory.

Step-by-step instructions

  1. Check the filename and folder for clues, such as .dwg.bak, .txt.bak, a SQL Server backup folder, or an application-specific backup directory.
  2. If it is a SQL Server backup, restore it using Microsoft SQL Server restore tools rather than double-clicking the file.
  3. If it is an AutoCAD drawing backup, make a copy, rename the copy from .bak to .dwg, and open it in AutoCAD.
  4. If it appears to be a text or configuration backup, right-click it, choose Open with, and try a trusted text editor such as Notepad or another editor.

Alternative methods

  • Open .BAK in a browser-based viewer if desktop apps fail.
  • Try opening .BAK on Windows with a secondary app to rule out app-specific issues.
  • Convert .BAK only with trusted tools when direct opening is not possible.

Common issues

The .BAK file does not open when double-clicked

This is normal because .BAK is a generic backup extension and the operating system may not know which program created it.

  1. Look at the filename, folder, and related files to identify the original application or original extension.
  2. Try opening a copy with the program that created the backup.
  3. If the file is small and likely text-based, inspect it with a text editor.

SQL Server .BAK opens as unreadable data

A SQL Server .BAK file is a database backup, not a document or spreadsheet. It must be restored through SQL Server tools.

  1. Do not edit the .BAK file in a text editor.
  2. Use SQL Server restore functionality to restore the backup to a database.
  3. Restore to a test or non-production database first if you are unsure what the backup contains.

AutoCAD drawing backup will not open

AutoCAD .bak files are backup copies of DWG saves. They usually need to be renamed to .dwg before opening.

  1. Make a copy of the .bak file.
  2. Rename the copy so the extension is .dwg.
  3. Open the renamed copy in AutoCAD.

The restored file is corrupt or incomplete

The backup may have been interrupted, copied incompletely, created by a different application version, or not actually be the file type you expected.

  1. Compare the file size with other known-good backups from the same source.
  2. Get a fresh copy from the original system or backup location if possible.
  3. Try restoring with the exact application that created the backup, or a compatible version.

Security note

.BAK files can contain sensitive data, including full databases, drawings, configuration files, browser data, or personal documents; treat them as confidential backups.

Back to .BAK extension page