OCRopus is really a collection of document analysis programs, not a turn-key OCR system.
In addition to the recognition scripts themselves, there are a number of scripts for ground truth editing and correction, measuring error rates, determining confusion matrices, etc. OCRopus commands will generally print a stack trace along with an error message; this is not generally indicative of a problem (in a future release, we’ll suppress the stack trace by default since it seems to confuse too many users).
To recognize pages of text, you need to run separate commands: binarization, page layout analysis, and text line recognition. Here is an example for a page of Fraktur text (German); you need to download the Fraktur model from tmbdev.net/ocropy/fraktur.pyrnn.gz to run this example: