Commodore Error Messages is a concise two-page reference sheet explaining error and status messages for Commodore B-Series computers, including common BASIC problems such as syntax errors, bad subscripts, type mismatches, missing files, device errors, division by zero, out-of-memory conditions, and disk or tape verification failures. It also lists numbered ERR$(X) messages with expanded explanations, helping programmers diagnose problems in program flow, input/output operations, arrays, calculations, file handling, and storage media.