ES Upgrade from 5.6 to 6.8

[Indu_Nallithodi]

After upgrade to 6.8.0 as rolling upgrade:partial update is giving Validation exception
/_update?refresh=true
{"error":{"root_cause":[{"type":"remote_transport_exception","reason":"[node-02][:9300][indices:data/write/update[s]]"}],"type":"illegal_argument_exception","reason":"Validation Failed: 1: ifSeqNo is unassigned, but primary term is [4];"},"status":400}

The documentation says these parameters are optional to _update.
How to fix this on transit documents on rolling upgrade

Same operation works on a cluster which already running on 6.8 without any additional param other than 'refresh'

[nhat (Nhat Nguyen)]

Hi @Indu_Nallithodi

Thank you for reporting this. I will try to reproduce the issue and give you an update soon.

[nhat (Nhat Nguyen)]

Hi @Indu_Nallithodi

Unfortunately, there's a bug where we might not be able to partially update documents which are created in a mixed cluster between 5.x and 6.x. I opened https://github.com/elastic/elasticsearch/pull/46198 to propose the fix.

A workaround is to reindex those documents. The following query should return those documents.

  "query": {
        "term": {
            "_seq_no": -2
        }
    }

[Indu_Nallithodi]

Thanks @nhat for addressing this

So could you please confirm will we get the fix with 6.8.0 rpm soon?
If not yet ready would you be able to update when will be available, this will help in our rollout planning

Thanks
Indu

[nhat (Nhat Nguyen)]

Hi @Indu_Nallithodi, The fix will be included in the 6.8.4. We don't share the released dates of the upcoming versions.

[Indu_Nallithodi]

Thanks Nhat for the updates