Internal administrator health check fails with a SQL error

2016-12-16 13:42:33,116 ERROR [SupportHealthCheckThread-1] [healthcheck.directory.internal.InternalAdminCheck] check An error occurred when performing the Internal Administrator User healthcheck:
 -- referer: http://localhost:5108/confluence/plugins/servlet/stp/view/ | url: /confluence/rest/supportHealthCheck/1.0/check/process/ | traceId: 80050b4535a35221 | userName: admin
net.sf.hibernate.exception.SQLGrammarException: Could not execute query
	at net.sf.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:58)
	at net.sf.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
	at net.sf.hibernate.impl.SessionImpl.convert(SessionImpl.java:4151)
	at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1573)
	at net.sf.hibernate.impl.QueryImpl.list(QueryImpl.java:49)
	at net.sf.hibernate.impl.AbstractQueryImpl.uniqueResult(AbstractQueryImpl.java:550)
	at com.atlassian.confluence.plugins.healthcheck.directory.internal.InternalAdminCheck.countUsersInAdminGroupQuery(InternalAdminCheck.java:125)
	at com.atlassian.confluence.plugins.healthcheck.directory.internal.InternalAdminCheck.check(InternalAdminCheck.java:87)
	at com.atlassian.support.healthcheck.impl.PluginSuppliedSupportHealthCheck.check(PluginSuppliedSupportHealthCheck.java:41)
	at com.atlassian.support.healthcheck.concurrent.SupportHealthCheckTask.run(SupportHealthCheckTask.java:33)
	at com.atlassian.support.healthcheck.concurrent.SupportHealthCheckProcess.run(SupportHealthCheckProcess.java:43)
	at com.atlassian.support.healthcheck.thread.HealthCheckProcessCallable.call(HealthCheckProcessCallable.java:44)
	at com.atlassian.support.healthcheck.thread.HealthCheckProcessCallable.call(HealthCheckProcessCallable.java:20)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: org.postgresql.util.PSQLException: ERROR: operator does not exist: character varying = bytea
  Hint: No operator matches the given name and argument type(s). You might need to add explicit type casts.
  Position: 581
	at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2157)
	at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1886)
	at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:555)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:417)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:302)
	at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:379)
	at net.sf.hibernate.impl.BatcherImpl.getResultSet(BatcherImpl.java:89)
	at net.sf.hibernate.loader.Loader.getResultSet(Loader.java:880)
	at net.sf.hibernate.loader.Loader.doQuery(Loader.java:273)
	at net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:138)
	at net.sf.hibernate.loader.Loader.doList(Loader.java:1063)
	at net.sf.hibernate.loader.Loader.list(Loader.java:1054)
	at net.sf.hibernate.hql.QueryTranslator.list(QueryTranslator.java:854)
	at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1570)
	... 13 more