Symptoms

A newly scanned input file does not split, and appears with message 'Error rebuild failed: trailer not found'

Causes

The scanned PDF file is corrupted before Symphony Profiler begins reading it.

There are several reasons that this can happen - by far, the most common is that the scanner generated an invalid PDF (either something went wrong in the scanner, or the network connection between the scanner and the target network folder was interrupted before the entire file could be copied.

There is also the possibility that Symphony Profiler is attempting to read the file before the scanner has finished writing the file.  This is unlikely, as Symphony Profiler waits until the input file has not been changed for 30 seconds (note: this 30 seconds value can be adjusted using Edit->Preferences->Monitored Folders, then choose the folder, click Edit and adjust the 'Only find files older than' value)

Resolution

To confirm that the issue is the scanner, you can temporarily change the 30 second timeout to be 300 seconds, then see if the issue continues.  This will delay how quickly Symphony Profiler will process files after they are scanned.  If the problem continues, then something is wrong with the scanner.

If the problem does not continue, then there may be something wrong with the speed that the scanner is able to write the PDF to the network (it is very unusual that a scanner wouldn't update the scan PDF within 30 seconds).