Note: You are currently viewing documentation for Moodle 2.1. Up-to-date documentation for the latest stable version is available here: error/debug/codingerror.
Coding errors (or coding_exceptions) are problems that are probably caused by incorrect code. For example a plugin that does not communicate correctly with Moodle core.
These errors are normally not caused by incorrect user input or temporary problems like the connection to the database server being down.
Tip: We had this error appear during restore of a v1.9 backup to a v2.1 site. (The Moodle version may or may not be significant.) It was caused by the presence of three multiple-choice Questions which didn't have any answers defined. Beats me how the teacher managed to create those questions. Error messages during the Backup part of the process helped us locate and delete the offending questions.