I'm trying to use the TaggedReadPreference with the Java driver when
reading from a replica set. It seems to work as long as I specify a
secondary tag. When I specify the primary tag, I get the following
exception:

com.mongodb.MongoException: Could not find any valid secondaries with
the supplied tags ('

{ "locale" : "sc"}

'
at com.mongodb.DBTCPConnector$MyPort.get(DBTCPConnector.java:358)
at com.mongodb.DBTCPConnector.call(DBTCPConnector.java:212)
at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:305)
at com.mongodb.DBCollection.findOne(DBCollection.java:647)
at com.mongodb.DBCollection.findOne(DBCollection.java:626)

I also tested reading from the secondary and killing the primary. When
the secondary is elected the primary, the read fails with the same
exception above (just with a different locale).

My code looks like:

HashMap<String, String> tags = new HashMap<String, String>(1);
tags.put("locale", "sc");
...
dbCollection.setReadPreference(new
ReadPreference.TaggedReadPreference(tags));

My replica set is configured as:

PRIMARY> rs.conf()
{
"_id" : "test",
"version" : 3,
"members" : [
{
"_id" : 0,
"host" : "localhost:27020",
"priority" : 2,
"tags" :

{ "locale" : "sc" }

},
{
"_id" : 1,
"host" : "localhost:27021",
"tags" :

{ "locale" : "in" }

},
{
"_id" : 2,
"host" : "localhost:27022",
"tags" :

{ "locale" : "de" }

}
]