I use AddThis Share Buttons on my site (this add-on was installed in ready-made WP theme). I have four social buttons: FB, Twitter, VK and LinkedIn.
The problem is that when you try to share the post, the page gets error 400. In different browsers different buttons doesn't work: Chrome 46 — twitter, vk, linkedin; FF 42 — vk, linkedin; IE11 — all buttons work (:D)
I think it's because of too long request - but I can be wrong. How to struggle it? Maybe someone had similar problems?