Recently, I am facing a strange problem when using krige() in gstat library. This error was not there a few months ago because I am using the same code with the same data that I successfully used before. But now I am getting singular covariance matrix at grid points at which I want to krige the unknown values. I changed nothing in that old code. Just opened and ran, and now it would not run. Upon searching I found one solution set=list(cn_max = 1e10) from a communication between Edzer and Hengl under title "[R-sig-Geo] 'LDLfactor' error in 'krige' function". However, then krige() gives syntax error about cn_max. I also read "Error in In predict.gstat in R" question on this site, but it also does not work for me.
Why I am getting this error suddenly?