Could not pack/validate JSON response

Elastic Stack Elasticsearch
1

Hi Team,

Hope you are doing well..

I am getting below error in fluentbit.log for some indexes these logs/indexes are getting from application servers and we are managing this on our elasticsearch servers which consist of kibana,elasticsearch and fluentbit , can you please assist me with this.

Elasticsearch and Kibana version :- 8.19.4

Fluent bit version :- 3.2.10

Fleuntbit configuration e.g

[INPUT]
    alias forward_gather_all_logs
    buffer_max_size 4G
    listen 0.0.0.0
    name forward
    port 123
    storage.type filesystem
    threaded on
    tls on
    tls.crt_file /etc/elasticsearch/ssl/elasticsearch.crt
    tls.debug 4
    tls.key_file /etc/elasticsearch/ssl/elasticsearch.key
    tls.verify off
...
...
...
...
...
...

[OUTPUT]
    alias es_uat_sytems
    buffer_size 2048KB
    host 1.2.3.4
    http_passwd admin
    http_user admin
    logstash_format on
    logstash_prefix log-uat-system
    match uat.platform.***
    name es
    port 9200
    retry_limit no_limits
    storage.total_limit_size 512M
    suppress_type_name on
    tls on
    tls.verify off
    trace_error on

[2025/10/05 00:01:27] [ warn] [engine] failed to flush chunk '1550332-1759302168.810621713.flb', retry in 7 seconds: task_id=164, input=storage_backlog.7 > output=es_uat_system (out_id=23)
[2025/10/05 00:01:34] [ warn] [http_client] cannot increase buffer: current=2048000 requested=2080768 max=2048000
[2025/10/05 00:01:34] [error] [output:es:es_uat_system] could not pack/validate JSON response
{"errors":false,"took":400,"items":[{"create":{"_index":"log-uat-system-2025.09.25","_id":"_28-sZkBJSmdNVS4nBLW","_version":1,"result":"created","_shards":{"total":2,"successful":2,"failed":0},"_seq_no":9955965,"_primary_term":4,"status":201}},{"create":{"_index":"log-uat-system-2025.09.25","_id":"AG8-sZkBJSmdNVS4nBPW","_version":1,"result":"created","_shards":{"total":2,"successful":2,"failed":0},"_seq_no":9955966,"_primary_term":4,"status":201}},{"create":{"_index":"log-uat-system-2025.09.25","_id":"AW8-sZkBJSmdNVS4nBPW","_version":1,"result":"created","_shards":{"total":2,"successful":2,"failed":0},"_seq_no":9955967,"_primary_term":4,"status":201}},{"create":{"_index":"log-uat-system-2025.09.25","_id":"Am8-sZkBJSmdNVS4nBPW","_version":1,"result":"created","_shards":{"total":2,"successful":2,"failed":0},"_seq_no":9955968,"_primary_term":4,"status":201}},{"create":{"_index":"log-uat-system-2025.09.25","_id":"A28-sZkBJSmdNVS4nBPW","_version":1,"result":"created","_shards":{"total":2,"successful":2,"failed":0},"_seq_no":9955969,"_primary_term":4,"status":201}},{"create":{"_index":"log-uat-system-2025.09.25","_id":"BG8-sZkBJSmdNVS4nBPW","_version":1,"result":"created","_shards":{"total":2,"successful":2,"failed":0},"_seq_no":9955970,"_primary_term":4,"status":201}},{"create":{"_index":"log-uat-system-2025.09.25","_id":"BW8-sZkBJSmdNVS4nBPW","_version":1,"result":"created","_shards":{"total":2,"successful":2,"failed":0},"_seq_no":9955971,"_primary_term":4,"status":201}},