Indicates files that are missing or are currently in use.
In order to migrate a project successfully, AutoCAD P&ID must be able to place an exclusive lock on all files related to the project. The File Unavailable page is displayed if a file related to the project is missing, or if a file is currently in use. For example, you moved a drawing or deleted a file from the project folder, or someone is editing a drawing using AutoCAD P&ID 2009.
Until a project and its related drawings are available and locked, migration to AutoCAD P&ID 2015 cannot proceed.
If files are missing or in use, the File Unavailable page lists the invalid files. The file name, location path, and status are displayed. 
indicates a missing file, and 
indicates a file that is currently in use.
Before beginning migration, do the following:
- Locate any missing files and move them to the project directory.
- Close all files currently in use.
- View Migration Log
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Displays the migration log, where you can find further information about missing files or files that are still in use.