How to fix the "Execution of parallel task failed: grayComponent.frdat could not be opened because there are too many open files"?

Symptoms

The warning message Execution of parallel task failed: grayComponent.frdat could not be opened because there are too many open files appears once running the FineReader Engine 12 application.

Cause

The reason for this issue could be that during processing FineReader Engine 12 tries to open more temporary files than allowed by the operating system.

Resolution

This is a known issue, and for FineReader Engine 12 for Linux, the following note is included in the Developer's Guide article Specifications → System requirements:

For multi-page documents synthesis and export, please set the open files limit to be no less than 2000. Run ulimit -n [limit_size] to change it.