This error occurs when the version of the Microsoft Sandcastle documentation tools found is not the most recent version.

The following information can help solve this problem:

• Review the Installation Instructions carefully and make sure that you have installed all of the required tools and have the latest version of each.
• Check to be sure that a system copy of the DXROOT environment variable exists and that it points to the most recent copy of Sandcastle (usually C:\Program Files\Sandcastle). In addition, make sure that there is no user copy of the DXROOT environment variable. If one does exist, delete it.
• If the Sandcastle folder exists in the PATH environment variable, ensure that it is correct. Preference is given to the DXROOT variable so this is not a requirement unless the DXROOT value is wrong.
• If all else fails, manually specify the location of the Sandcastle tools by entering the path in the SandcastlePath project property. This usually needs to be done if performing the build on a build server.

Note
In all cases above, be sure to specify the path to the Sandcastle tools from Microsoft, NOT the path to the help file builder.

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