title: glGenTextures gives GL_INVALID_OPERATION despite valid OpenGL context
body: <p>I get a <code>GL_INVALID_OPERATION</code> error when calling <code>glGenTextures</code> and I have no idea what could be responsible for it. </p>
  
  <p>I am using QtOpenGLWidget to retrieve the context and it looks valid  at the time I call <code>glGenTextures()</code> (at least I have one since <code>glGetString(GL_VERSION)</code> and <code>glxGetCurrentContext()</code> both return something which is not crap)</p>
  
  <p>The faulty code is called from the <code>QOpenGLWidget::resizeGL()</code> method. In the <code>QOpenGLWidget::initializeGL()</code> I compile successfully some shader programs and I create / upload data to VAO / VBOs.</p>
  
  <p>So my questions are :</p>
  
  <ul>
  <li>What are the common faulty cases of <code>glGenTextures()</code> except not having an OpenGL context at all</li>
  <li>Can an OpenGL context be invalid or messed up and, in such a case</li>
  <li>How can I check that my OpenGL context is valid ?</li>
  </ul>
  
  <p>EDIT: Since I strongly believe this is related to the fact my machine has no proper GPU, <a href="https://gist.github.com/Zouch/7f011dd18d7a9093ba8734d1ca0f16a0" rel="nofollow">here is the return of glxinfo</a>.</p>