grep - R: Error in nchar(b64String) : invalid multibyte string, element 1 -

i using illuminaio::readidat read idat files.

library(illuminaio) dat <- readidat('1552034262_a_grn.idat') error in nchar(b64string) : invalid multibyte string, element 1 in addition: warning messages: 1: in grep(" __", r) : input string 47890 invalid in locale 2: in grep(" __", r) : input string 47891 invalid in locale 3: in grep(" __", r) : input string 47892 invalid in locale 4: in grep(" __", r) : input string 47893 invalid in locale 5: in grep(" __", r) : input string 47894 invalid in locale 6: in grep(">", r) : input string 47890 invalid in locale 7: in grep(">", r) : input string 47891 invalid in locale 8: in grep(">", r) : input string 47892 invalid in locale 9: in grep(">", r) : input string 47893 invalid in locale 10: in grep(">", r) : input string 47894 invalid in locale 

this sessioninfo():

r version 3.3.1 (2016-06-21) platform: x86_64-pc-linux-gnu (64-bit) running under: centos release 6.7 (final)  locale:  [1] lc_ctype=en_us.utf-8       lc_numeric=c                [3] lc_time=en_us.utf-8        lc_collate=en_us.utf-8      [5] lc_monetary=en_us.utf-8    lc_messages=en_us.utf-8     [7] lc_paper=en_us.utf-8       lc_name=c                   [9] lc_address=c               lc_telephone=c             [11] lc_measurement=en_us.utf-8 lc_identification=c         attached base packages: [1] stats     graphics  grdevices utils     datasets  methods   base       other attached packages: [1] illuminaio_0.15.1  loaded via namespace (and not attached): [1] base64_2.0    openssl_0.9.4 

i getting error don't know how debug it. appreciated.