When an error occurs, it is recorded in this state variable and no further errors are recorded. Reading errors returns the currently recorded errors (there may be more than one due to a possibly distributed implementation) and resets the state variable to , re-enabling the recording of future errors. The value  means that there has been no detectable error since the last time errors was read, or since the GL was initialized.
GL/GLU errors consist of a general error category and a description of what went wrong.
General GL/GLU error categories
This module corresponds to section 2.5 (GL Errors) of the OpenGL 2.1 specs and chapter 8 (Errors) of the GLU specs, offering a generalized view of errors in GL and GLU.