MongoDB FeatureCompatibilityVersion

Description

This check warns if there is a mismatch between the MongoDB version and the value of the internal FCV (Feature Compatibility Version) parameter.

Resolution

FeatureCompatibilityVersion (FCV) enables or disables the features that persist data incompatible with earlier versions of MongoDB.

If there is a mismatch between the MongoDB version and the FCV parameter, make sure to set the FCV according to the MongoDB version. See below the values associated with FCV.

Deployments	FCV
For 6.0 deployments upgraded from 5.0	“5.0” until you setFeatureCompatibilityVersion to “6.0”.
For 5.0 deployments upgraded from 4.4	“4.4” until you setFeatureCompatibilityVersion to “5.0”.
For 4.4 deployments upgraded from 4.2	“4.2” until you setFeatureCompatibilityVersion to “4.4”.
For 4.2 deployments upgraded from 4.0	“4.0” until you setFeatureCompatibilityVersion to “4.2”.

To view the featureCompatibilityVersion for a mongod instance, run the getParameter command on a mongod instance:

db.adminCommand( {
                    getParameter: 1,                    
                    featureCompatibilityVersion:     
                  }
               )

To set the Feature Compatibility Version, run the command against the admin database. For example, to set the FCV on MongoDB version 6.0, run the following command -

db.adminCommand( { setFeatureCompatibilityVersion: "6.0" } )

For more information on FCV, see the MongoDB Documentation.

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