Webgl 2.0 context seems to expect only GLSL 3.00 shaders, even when the #version 300 es is omitted. The webgl 2.0 spec clearly indicates that webgl 2.0 should support both GLSL 1.00 and GLSL 3.00 shaders. Although I cannot find it in the spec, the overwhelming consensus seems to be that 2.0 shaders are by default GLSL 1.0 unless the version directive is included. When provided a GLSL 1.00 shader, I get the following error: WebGL: ERROR: 0:1: " : #version required and missing.