Error when starting opensearch - failed to parse field [index_template]

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
Opensearch 2.6.0 (installed via debian package) migrating from ElasticSearch 7.17.6

Describe the issue:
On startup, the command ‘service opensearch start’ does not return and the logs are reporting:

[index_template] failed to parse field [index_template]

I’m following the rolling upgrade documentation. could it be that the ES version to high for migration?


I’m facing a very similar issue:

org.opensearch.common.xcontent.XContentParseException: [-1:17135] [persistent_tasks] failed to parse field [tasks]

I am also elastic 7.17.9, so my guess is, that after 7.10.X there were new fields introduced into elastic that open search can not parse

I would be very happy to hear any ideas

Yes, it might be down to some breaking changes between ES 7.10 and 7.17. Maybe you can upgrade by spinning up a new cluster? I’m not sure if snapshot/restore will work well for the same reason - maybe it would if you only snapshot the data and not the cluster state.

yeah, I tried to restore a snapshot but that didn’t work either… In the end I just started from scratch in a new container and now I’m facing radon opensearch crashes
If that persists I’ll open another thread. Thanks for the help though.