Mybatis-Plus报错optimize this sql to a count sql has exception是为什么？-灵析社区

mybatis报错：optimize this sql to a count sql has exception：…………………… exception: null 我的sql语句是这样的： (select distinct projects.*,unitUser.uname as unitName,adminUser.uname as userName from projects inner join unitUser on projects.unitId=unituser.id inner join adminProject on adminProject.projectId = projects.id inner join adminUser on adminUser.id = adminproject.userId ${ew.customSqlSegment} ) UNION (select distinct projects.*,unitUser.uname as unitName,null as userName from projects inner join unitUser on projects.unitId=unituser.id and projects.id not in ( select projects.id from projects inner join adminProject on adminProject.projectId = projects.id ) ${ew.customSqlSegment} ) mybatis-plus的版本是4.0以上的，在网上看了博客报错的都是3.4，3.5；  该mapper方法的形参是这样的，ew是我的一个queryWrapper。