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Cause

CMJ finds matching configuration objects for the snapshot on the target system. Usually configuration objects are matched by their name (or key for projects, name+type for custom fields, etc.). However for default schemes CMJ always tries to match the default scheme from the snapshot to the default scheme on the target disregarding the name

It seems that you have a scheme in the snapshot that is named with the same name as the default scheme on the target, where it is probably not default ("default software scheme") – this way they don’t get properly matched and a new scheme is trying to be created unsuccessfully. We have an issue open for this case - CMJ-97

Resolution

The best known workaround is to just rename the scheme on the source JIRA and deploying a new snapshot without a scheme with the same name as the default on the target that isn't default. 

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'Default software scheme' is not really default.

Most often this is caused by schemes with the same name in the snapshot and the target instance, one of which is default, while the other is not.

For some object types, CMJ matches default objects in the snapshot to their default counterparts in the target instance. Those include permission schemes, issue type schemes, notification schemes, field configuration schemes, field configurations, workflows. Non-default objects are matched by name. If a matching object is not found in the target instance, a new one will be created using the name of the object in the snapshot.

Resolution

• If you'd like the permission scheme in the snapshot to match the one in the target instance, make sure they are either both default, or that they are both non-default and have the same name.
• To make sure the default scheme is not exported, create a copy of it and assign it to the exported projects. Rename it if necessary.