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Posts cause errors in Vanilla 2.1
This discussion is related to the SecureDice addon.

Since upgrading to Vanilla 2.1, if I enable this plugin, whenever you add a comment to a thread I get the error message: "There was an error performing your request. Please try again."
However, if I refresh the page, I see that the post was actually posted. If I disable Secure Dice the problem goes away.
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Comments
something to report here as well. if you want to put the info in one place.
also try sending the author a message to fix it.
http://vanillaforums.org/discussion/26703/plugins-themes-that-work-and-don-t-work-in-vanilla-2-1
I may not provide the completed solution you might desire, but I do try to provide honest suggestions to help you solve your issue.