The original extension specification which defines this behavior states that GL_INVALID_OPERATION is generated when SAMPLE_BUFFERS for EITHER the read framebuffer or draw framebuffer is greater than zero. However, the reference page states that GL_INVALID_OPERATION is generated when SAMPLE_BUFFERS for BOTH framebuffers is greater than zero, conflicting with the specification.
The original extension specification which defines this behavior states that GL_INVALID_OPERATION is generated when SAMPLE_BUFFERS for EITHER the read framebuffer or draw framebuffer is greater than zero. However, the reference page states that GL_INVALID_OPERATION is generated when SAMPLE_BUFFERS for BOTH framebuffers is greater than zero, conflicting with the specification.