Adobe Acrobat could not load the search index associated with the document

When you open a PDF document that has an associated index, Acrobat prompts you to load the index file, but when you click Load, the following error message is displayed:

"Adobe Acrobat could not load the search index associated with this document (<location of .pdx file>). The index is either corrupt or is not compatible with this version. Searching within this document will therefore be slower. You may wish to rebuild this index using Adobe Acrobat Pro's Catalog feature or contact the document creator."

Solution: Manually search for the associated index file