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What is the .MST File Extension?

.MST File Extension Description:

The .mst file extension is described as the Microsoft Windows Installer. It contains modifications and instructions that can be applied to the package during Setup installation of a Microsoft Project. The .mst file modifies the MSI file, which is a database describing the different components used in Microsoft Project, as well as the information regarding configurations and instructions on how the installation will proceed.

Through the use of the files with the .mst format to the base installation package, the installer can replace or add data found in the installation database. However, the mechanism of the files with .mst extension can only be applied during the installation process.

There is a list of modifications with the file extension MST required by the product during the installation that the installer will register into the system. As such, the installer is required to apply the files with the .mst extension to the installation package of the product when installing or configuring it.

In case the listed and required file with the .mst file is unavailable, or if the source resiliency of the modification cannot restore the file with the .mst file extension, the installation will result in a failure.

The files with the .mst extension have the capability to modify information included in any persistent table in the installer database. Additionally, the file extension MST can remove or add these tables in the installer database. Files with the .mst cannot modify any part of the installation package not included in the database table. Such parts include the information within the sub-storages, summary information stream, or the files in the embedded cabinets.

The file extension MST also contains its own summary information stream that contains conditions for validation and error during runtime of the installation. By using the "MsiCreateTransformSummaryInfo" function, the error and validation conditions of the file with the .mst extension can be integrated towards the summary information stream.

The validation conditions of the file extension MST handles whether the installer is allowed or has the ability to apply the changes to the installation database or not. On the other hand, the error conditions actually control the errors that get suppressed once the changes are applied.

Author: Microsoft
Author URL:
Related Applications: Microsoft Project Installer
Common Path: N/A


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Do you have errors with .MST files?

The Standard Cause of .MST files Errors:

A typical and frequent explanation for .MST files errors is failure in the Windows program registry - cleaning is necessary to avoid more damage in other software and/or hardware devices. Risks include device failure, blue screen errors and fatal crashes.

Symptoms of .MST files Errors:

.MST files error symptoms include application lock ups, start up or shut down troubles, slow system performance, sluggish behaviour, input halts, beeping sounds, problems loading program files and problems while installing programs.

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