I am also working on the same project as jefvel.
This is the code we add to the main loop that makes the text renderer's text rendering work. However, this code itself gives the same error:
http://pastebin.com/nNfFtERWSo with this code-snipped commented out, the text renderer breaks and gives the openGL error to the terminal. With it, the snipped itself breaks with that error, but the text renderer works.
The extra snippet is run before the text renderer.
We are using sf::RenderWindow for rendering and we draw stuff on it with raw openGL before rendering the text on it (in the case of the snippet, the text is rendered before the openGL rendering is done)
If we comment out our main loop that runs our whole game engine structure and replace it with this:
http://pastebin.com/svFQb3RAthen it works flawlessly, drawing the text.
Can there be any conflicting openGL code in the rest of our rendering system that conflicts with the text rendering of sfml?