Many people have tried in one way or another to ask about the mathematical prerequisites to study or understand string theory, but all their (up voted!) question have been and are being closed before they have a chance to get a nice answer.
String theory (and generally large parts of modern fundamental and theoretical physics) is quite a mathematical topic and to understand the physics of it, one obviously has to understand some mathematics too, so the expectation that one should be allowed to ask about the mathematical prerequisites and where one can find good introductory material to get started on a physics site, seems not too unreasonable to me. On the contrary, it would be helpful for many people to hear from physicists already working on the subject about what is needed concerning mathematical prerequisites.
Closing all these questions before they have a fair chance to get a nice answer is discouraging for people interested in the physics topic itself too and looks not very welcoming to them. (Qmechanic at least left a nice comment that the topic is in principle ok here). Closing all questions asking this is too bad since there is no such question with a nice canonical standard answer here on physics SE, where people interested in the issue could be pointed to.
Could an answer to the question, what are important mathematical prerequisites to understand string theory (which includes some pointers to good introductions) be worked out as an answer to this meta post (since it is obviously not allowed to give an answer directly on the main page), and then be attached to one of the closed questions about this issue by a moderator or another powerful enough user to "migrate" it? Future questions about this issue could then rightly so be closed as duplicates and people interested in the issue pointed to this canonical standard answer.