"<file" java.lang.unsupportedoperation exception when indexing data

Im trying to index data through Logstash. which each document is of size 400kb. around 1500 documents.
got the following error. after indexing some data.
can any one help me . what this is about..
when left for some time and try indexing data again ,Able to index some data again.
#elasticsearch #logstash