Symptoms

InitializeEngine returns error as a non-root user with a runtime license

Works as root user with runtime license
Works as either root or non-root user with a developer license
Nothing obvious (e.g. permission denied errors) in strace output, Network, or Protection logs.

A variation of the error message in engine logs may look like this: 

The launch of the ABBYY product has been interrupted. Some files may have been corrupted.
Please reinstall the program or contact your system administrator.
Error code: 0

Solution

Usually, this type of issue is caused by insufficient permissions applied to files in the Engine root folder, by default /opt/ABBYY and /var/lib/ABBYY

The general recommendation, in this case, will be to double-check the permission for the mentioned folders and files in them. 

Also, for testing purposes, we do recommend applying chmod 777 -R to specified folders in order to eliminate the possibility.

General recommendations and specific permission levels are described in this documentation entry: Basic Installation Scenarios