Hi , I am new here , so hello to everyone 
Last week I started using graylog server for collecting logs from vCSA.
and there was no problem ,at least I thought so. After four hours it seemed to stop indexing .
Greylog received a message on interface but there were some problem .
On overview page there is line :
There were 204,794 failed indexing attempts in the last 24 hours.
a few seconds ago graylog_0 e4630a50-534b-11ea-8c3a-005056a0b7bf {“type”:“cluster_block_exception”,“reason”:“blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];”}