Posted: 2/17/2010, Updated: 9/28/2012
The error, "The filter returned an error" may appear in the client log for any version or edition of the Identity Finder client software. This error indicates that Identity Finder was unable to extract text from the specified file and therefore it was not searched (unless an alternate filter was used and successful - see Additional Information for more detail).
When searching files, Identity Finder will first attempt to use an internal filter to extract text from the file. If no internal filter is available, Identity Finder will look for a default Windows or third-party IFilter (Windows) or a Spotlight Plugin (Mac OS).
There error most commonly appears when an IFilter is used for text extraction. IFilters are invoked based on the extension of the target file - for example - when searching a file named, "test.doc", the default Microsoft Word IFilter will be invoked. If the extension of the file does not match the actual type of the file, the IFilter will be unable to extract text from that file and the location will not be searched. For example, if "test.doc" is really a plain text file, then the IFilter will determine that the file is not a Microsoft Word document and will return this error. Additionally, some versions of Microsoft Office Template files will also return this error because there is no content to search within the file itself.
The most common causes of this error are text files renamed as .doc files and csv files renamed as .xls files.
For PDF files, there are a number of errors within the PDF structure itself that will prevent them from being properly opened. If the log entry is a PDF file and that file cannot be opened with Adobe Acrobat or Acrobat "repaired" the file when it was opened, then the file contained/contains errors that were the cause of the Identity Finder error.
Identity Finder for Windows version 4.5 and later include the advanced file type identification feature to allow automatic detection of file types, regardless of their extension, when this error is encountered.