knitr problem after update to R 3.0.0

I just updated R to 3.0.0. I couldn't compile PDF from my .Rnw file, which I could do with R 2.15. Here is the error I got:

! Undefined control sequence.
l.192 \SweaveOpts
{concordance=TRUE}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., \hobx'), type I' and the correct
spelling (e.g., I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.


It seems related to Sweave. But I was using knitr to weave .Rnw file. Could some one help me fix the problem?

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Remove \SweaveOpts{concordance=TRUE} in your Rnw file. It is invalid and useless to knitr`.