MongoDB 6.0 upgrade: IncompatibleCollationVersion (more help needed)

Graylog Central (peer support)
1

1. Describe your incident:

Attempting to upgrade MongoDB to 6.0 and getting the following error when trying to start:

IncompatibleCollationVersion: Requested collation version 57.1 but the only available collator version was 76.1

{"t":{"$date":"2025-08-08T03:16:19.332-04:00"},"s":"F",  "c":"INDEX",    "id":28782,   "ctx":"initandlisten","msg":"Found an invalid index","attr":{"descriptor":{"v":2,"key":{"title":1},"name":"title_1","collation":{"locale":"en","caseLevel":false,"caseFirst":"off","strength":3,"numericOrdering":false,"alternate":"non-ignorable","maxVariable":"punct","normalization":false,"backwards":false,"version":"57.1"}},"namespace":"graylog.views","error":"IncompatibleCollationVersion: Requested collation version 57.1 but the only available collator version was 76.1. Requested collation spec: { locale: \"en\", caseLevel: false, caseFirst: \"off\", strength: 3, numericOrdering: false, alternate: \"non-ignorable\", maxVariable: \"punct\", normalization: false, backwards: false, version: \"57.1\" }"}}
{"t":{"$date":"2025-08-08T03:16:19.332-04:00"},"s":"F",  "c":"ASSERT",   "id":23091,   "ctx":"initandlisten","msg":"Fatal assertion","attr":{"msgid":28782,"file":"src/mongo/db/catalog/index_catalog_impl.cpp","line":548}}
{"t":{"$date":"2025-08-08T03:16:19.332-04:00"},"s":"F",  "c":"ASSERT",   "id":23092,   "ctx":"initandlisten","msg":"\n\n***aborting after fassert() failure\n\n"}

2. Describe your environment:

  • OS Information: FreeBSD

  • Package Version: 6.2.3

  • Service logs, configurations, and environment variables:

3. What steps have you already taken to try and solve the problem?

Followed instructions at: Upgrade a Standalone to 6.0 - Database Manual v6.0 - MongoDB Docs

Looked at forum post: MongoDB 6.0 upgrade: IncompatibleCollationVersion

Reverted back to 5.0 and ran the command to drop Indexes:

> db.views.dropIndexes()
{
        "ok" : 0,
        "errmsg" : "ns not found test.views",
        "code" : 26,
        "codeName" : "NamespaceNotFound"
}
> db.views.getIndexes()
[ ]

4. How can the community help?

Need to know how to upgrade to 6.0 since 5.0 is deprecated.

2

Hello @tuaris,

What version of Graylog are you running, the error references Graylog Views which is an older feature.