300link.frag
Shader version: 300
0:? Sequence
0:8  Function Definition: main( (global void)
0:8    Function Parameters: 
0:?   Linker Objects
0:?     'color1' (out highp 4-component vector of float)
0:?     'color2' (out highp 4-component vector of float)


Linked fragment stage:

ERROR: Linking fragment stage: when more than one fragment shader output, all must have location qualifiers

Shader version: 300
0:? Sequence
0:8  Function Definition: main( (global void)
0:8    Function Parameters: 
0:?   Linker Objects
0:?     'color1' (out highp 4-component vector of float)
0:?     'color2' (out highp 4-component vector of float)