Error 3051: The Microsoft Jet database engine cannot open the file...

The complete text for the error is “The Microsoft Jet database engine cannot open the file <name>. It is already opened exclusively by another user, or you need permission to view its data.”

The text is completely misleading. The actual meaning is that the program is trying to open the Access database in Modify mode and it cannot do so because the file (or containing folder) is read-only.

Error 3051 when restoring Payroll System database


The backup folder or the MDB file could have the Read-Only attribute set. This will happen, for example, if the folder is copied from one computer to another via CD or DVD. The folder aquires the Read-Only attribute when copied to the disc; the attribute remains when it is copied from the disc to a hard drive.


For the solution, see Error 3051 when Restoring Payroll Data.

Error 3051 in a network environment


In this situation, the error is probably due to the user not having permission to modify the database.


See Your Network Data Is Read-Only.

Error 3051 in a single-user environment

One Computer, One User

In a single-user environment, the default location for the data is in the database folder inside of the program folder.  Read-write access should be available in that situation.

However, the database folder can be placed on a different hard drive. If the root of that drive is read-only, the folder must be created as an administrator, and security must be set so the user has modify access.

One Computer, Multiple Users

If a single computer mas multiple users, it may be necessary for an administrator to adjust the security settings on CFSLIB to allow other users to modify the contents of it and the contained folders, even if the program is installed to the default location.  

The default location for CFS programs is within the folder C:\CFSLIB. Some people prefer to install programs under C:\Program Files. This is not a good choice with Windows 7 and Vista. CFS programs need write access to the program folder during normal operation; in Windows 7 and Vista the Program Files folder is only accessible to program installers run by an administrator.

Another issue with installing the program in Program Files is that data storage is directed to “My Documents," which is not available to other users on the computer. If John installs the program, then Jane logs on to the same computer, Johns data will not be available. It is stored in John’s "My Documents" folder, which is not available to Jane.

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Error 3051 when Restoring Payroll Data

Error 3075 in Payroll System