Sometimes, if a PostScript file hasn't been exported properly or there is any other kind of problem that prevents Distiller from generating a PDF, the file is skipped and a text log file is created in the same location where the PostScript is located. The most common errors are due to memory problems, font issues, or corrupted PostScript files.
Font-related error messages usually have this form:
%%[ Error: invalidfont; OffendingCommand: findfont ]%%
An invalidfont type error usually occurs when a font used in the PostScript file is not present in any of the Font Locations folders or if the font is present but can't be embedded due to restrictions set in the font by its manufacturer. A less common error is when a font file has become corrupted.
Memory problems (not enough memory available) or corrupted PostScript file problems usually produce errors with this form:
%%[ Error: undefined; OffendingCommand: xxxx ]%%
where xxxx corresponds to a string of code that Distiller can't recognize.
Sometimes, if the error is caused by low memory available, shutting down other applications and re-sending the PostScript file to Distiller solves the problem. If the problem is a corrupted PostScript file, the only solution is to have it re-created.
Other errors can have more cryptic headers like exch or limitcheck. The first often refers to corrupted graphics embedded in the PostScript file, and the second to excessively complex vector objects. In both cases the only solution is to go back to the application that created the PostScript file and fix the problem there.