The pre-upgrade checker reports information about the status of your environment and the SharePoint sites in that environment, including:

• Upgrade readiness and supported paths   Returns a list of all servers and components in the farm and information about whether the servers meet requirements for upgrading.

• Alternate access mapping settings   Returns a list of the alternate access mapping URLs that are being used in the farm.

• Installed elements    Returns a list of all site definitions, site templates, features, and language packs that are installed in the farm. You need to know which site templates have been installed or used so that you can verify that they are available after an upgrade or database attach. You also need to know which elements have been customized so you can verify the customizations again after the upgrade. For example, you need to know whether a site depends on a language pack for Windows SharePoint Services 3.0 that does not exist yet for SharePoint Foundation 2010, so you can plan how to handle that site during upgrade.

• Unsupported customizations   Reports whether any server-side customizations that are not supported (such as database schema modifications) exist in the farm.

• Orphaned objects   Lists any database or site orphans in the farm. Objects such as list items, lists, documents, Web sites, and site collections can become orphaned — that is, the objects exist but are not associated with a particular site. Because orphaned objects do not work in the previous version, they won’t work after the upgrade. If you perform an in-place upgrade, the orphaned items will still exist, but will not work. We recommend that you repair any orphaned objects before upgrading.

  Tip:
  Members of the Administrators group on the front-end Web servers can repair orphaned items before the upgrade by following the steps in Knowledge Base article 918744, Description of a new command-line operation that you can use to repair content databases in Windows SharePoint Services (http://go.microsoft.com/fwlink/p/?linkid=69958&clcid=0x409).

• Valid configuration settings   Reports any missing or invalid configuration settings (such as a missing Web.config file, invalid host names, or invalid service accounts) that exist in the farm.

• Database requirements   Reports whether the databases meet the requirements for upgrade — for example, databases are set to read/write, and any databases and site collections that are stored in the Windows Internal Database are not larger than 4 GB.

Use the information gathered from the pre-upgrade checker to determine:

• Whether to perform an in-place upgrade or a database attach upgrade.

  Determine upgrade approach (SharePoint Foundation 2010) provides information to help you decide which type of upgrade to perform. It is important to consider the report generated by the pre-upgrade checker when you make this decision. If your servers do not meet the requirements for in-place upgrade, you need to consider performing a database attach upgrade.

• Whether to upgrade some or all site collections that contain customized sites.

• Which sites need to have customizations reapplied or redone after upgrade and therefore might take longer than others in the review stage.

A worksheet is available so you can record information about your environment while you prepare for upgrade. Download the worksheet from http://go.microsoft.com/fwlink/p/?LinkId=179928.

Before you perform this procedure, confirm that:

• Your system is running Windows SharePoint Services 3.0 with Service Pack 2

To run the pre-upgrade checker

After you run the pre-upgrade checker, the report automatically opens in your default browser. You can also view the report by opening it from its location in the %COMMONPROGRAMFILES%\Microsoft Shared\Web Server Extensions\12\LOGS directory. The report is named in the following format: PreUpgradeCheck_YYYYMMDD-HHMMSS-SSS-random-number.htm, where YYYYMMDD is the date and HHMMSS-SSS is the time (hours in 24-hour clock format, minutes, seconds, and milliseconds), and the random number is used to differentiate between possible simultaneous attempts to run the pre-upgrade checker. There are also TXT and XML versions of the report in the same location.

Use the report to find and troubleshoot issues. You can also share the relevant results with other members of the upgrade team. For example, you can report issues such as customized site templates or custom Web Parts to the appropriate site owner, Web designer, or developer before scheduling the upgrade, to give them time to resolve the issues.