Error message when you try to install an update for Visual FoxPro 8.0 or for Visual FoxPro 9.0: "The feature you are trying to use is on a network resource that is unavailable"

When you try to install an update for Microsoft Visual FoxPro 8.0 or for Microsoft Visual FoxPro 9.0, you may receive an error message that resembles the following error message:

This issue may occur for multiple reasons. These reasons include the following reasons:

• The Setup program cannot find the correct product .msi file in the Windows Installer cache.
  When you install Visual FoxPro 8.0 or Visual FoxPro 9.0, the Setup program saves the corresponding .msi file to the Windows Installer cache. This cached .msi file is referenced when you try to repair or to reinstall the product or when you apply an update to the product.
  
  In certain situations, the Setup program cannot find the .msi file in the Windows Installer cache. In these situations, the Setup program tries to resolve the source location by testing for the presence of the product installation. The Setup program does this in the location that was used when the Setup program was last run. If the Setup program cannot resolve the source location, the program prompts you to provide the installation media.
• There is a file hash mismatch.
  Updates for Visual FoxPro are based on Windows Installer. Windows Installer uses file version numbers to determine whether a file on the computer is an older version that must be replaced by a newer file that is contained in an update.
  
  Certain files, such as text files and source files, do not carry version numbers. Therefore, the Windows Installer-based update must use another method to verify newer files. This method uses a hash for all non-versioned files. For non-versioned files, the file hash of the file on the computer is compared to the file hash that is recorded in the Windows Installer database. If these two file hashes differ, the Setup program tries to fetch the file from the source installation media.
  
  Note Under certain circumstances, you might manually modify a file that was installed during the setup process. When you do this, file hash mismatches may occur. In this situation, you may be prompted to provide the installation media for the product when you try to install an update.
  
  There are valid reasons to manually modify a file that is installed during the setup process. For example, you might want to add a product key (PID) to the setup process for a licensed copy of Visual FoxPro before you put the product on a network share in your organization. You do this so that you do not have to share the PID with users who must install the product. Typically, this change is made in a text file that is named Setup.sdb. When you make such a change, the file hash for the file no longer matches the file hash that Windows Installer carries for the file in its database.

To work around this issue, insert the product installation CD in the computer's CD drive. Or, provide the path of the available installation media for the product. For example, the installation media may be available on the computer's hard disk or in a shared network folder.

If you are trying to deploy an update to many computers on which this issue occurs, we recommend that you use the /addsource command-line option.

How to use the /addsource command-line option

Recent software updates for Visual FoxPro 8.0 and for Visual FoxPro 9.0 include support for the /addsource command-line option. If you receive the error message that is mentioned in the "Symptoms" section when you try to install an update, use the /addsource command-line option. Use this command-line option to specify the location where you want Windows Installer to look for the files.

To use this command-line option, follow these steps.

Step 1: Verify that the software update that you are trying to install supports the /addsource command-line option

To do this, use either of the following command-line switches to open the usage dialog box:

• /?
• /help

If an update that support the /addsource command-line option is installed, this command-line option is displayed in the usage dialog box.

Step 2: Copy the Visual FoxPro installation media or an administrative image to a folder

Locate a folder that can be accessed from all the computers to which you want to apply the software update. Then, copy either of the following items to this folder:

• The Visual FoxPro installation media
  
  Note You must copy all the files from the installation media.
• A previously created administrative image for the Visual FoxPro product

Notes

• Typically, this folder is located on a network share.
• You must verify that the Vs_setup.msi file is in the folder that contains the Visual FoxPro installation media files. The Vs_setup.msi file is required when you use the /addsource command-line option.

Step 3: Use the /addsource command-line option

Use the /addsource command-line option when you install the software update. When you do this, use the following syntax in the command:

Name of the executable file for the update /addsource "Path of the Windows Installer package for the product"

Note In the command, replace the Path of the Windows Installer package for the product placeholder with the path of the Windows Installer package for the product that you copied to a folder in step 2.