quantmod and yahoo historical data download error - did yahoo changed the url?

it seems that these dates are not available.

Instead from="2014-09-17", to="2014-09-18":

rm(SPY)
getSymbols("SPY", from="2014-09-14", to="2014-09-16")

[1] "SPY"

SPY

SPY.Open SPY.High SPY.Low SPY.Close SPY.Volume SPY.Adjusted
2014-09-15   199.16   199.32  198.38    198.98   76350000       198.98
2014-09-16   198.61   200.84  198.50    200.48  116070400       200.48

Daniel