.BK1 File Extension

Autodesk Backup File

Developer Autodesk
2.9  |  12 Votes

What is a BK1 file?

Backup file created by Autodesk products, including AutoCAD Mechanical, Mechanical Desktop, and AutoCAD Map; stores a .BAK file that has been renamed with the ".bk1" extension; renamed when the Autodesk program terminates unexpectedly.

More Information

BAK files are automatically created when users save drawing files. Therefore, when a program crashes, Autodesk applications try to rename the BAK file to BK1 to prevent a corrupted drawing file from replacing the original backup.

NOTE: If the BK1 extension is already in use, Autodesk programs use ".bk2" through ".bk9," as well as ".bka" through ".bkz" and ".baa" through ".bzz" until a unique extension is found.

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Programs that open BK1 files

Windows Indexing Service File

Developer Microsoft
2.8  |  9 Votes

File created by Indexing Service, a component of Windows used to automatically index file system search information; contains information used for making fast file searches in Windows; typically seen with the name propstor.bk1.

More Information

BK1 files are often located within the C:\​System Volume Information\​catalog.wci\​ directory. Other catalog index files in this directory may include .BK2, .PS1, .PS2, .FID, .000, and .HSH files.

NOTE: Windows may also create BK1 files on external drives, such as USB flash drives.

Programs that open or reference BK1 files


ERwin Backup File

Developer CA
2.7  |  7 Votes

Backup file created by ERwin Data Modeler, a data modeling program; contains a backup of a .ER1 diagram file; created automatically by ERwin when the ER1 file is opened; used to recover a data model file if the original becomes corrupted.

More Information

BK1 files are used by older versions of ERwin Data Modeler.

Programs that open or reference BK1 files

CA ERwin Data Modeler

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