An Introduction to EGL - Praise for OpenGL ES 30 Programming Guide - page 62

reason that eglCreateContext would fail is if the EGLConfig we provide
is not valid, in which case the error returned by eglGetError is EGL_BAD_
CONFIG .

Example 3-6 shows how to create a context after selecting an appropriate
EGLConfig .

Example 3-6 Creating an EGL Context

const EGLint attribList[] =
{
// EGL_KHR_create_context is required
EGL_CONTEXT_CLIENT_VERSION, 3,
EGL_NONE
};

EGLContext context = eglCreateContext ( display, config,
EGL_NO_CONTEXT,
attribList );

if ( context == EGL_NO_CONTEXT )
{
EGLError error = eglGetError ( );

if ( error == EGL_BAD_CONFIG )
{
// Handle error and recover
}
}

Other errors may be generated by eglCreateContext , but for the
moment we will check for only bad EGLConfig errors.

After successfully creating an EGLContext , we need to complete one final
step before we can render.

Making an EGLContext Current

As an application might have created multiple EGLContext s for various
purposes, we need a way to associate a particular EGLContext with our
rendering surface—a process commonly called “make current.”