错误是：

This operation requires a connection to the ‘master’ database. Unable
to create a connection to the ‘master’ database because the original
database connection has been opened and credentials have been removed
from the connection string. Supply an unopened connection.

代码中没有任何变化 – 数据库访问在整个代码的其余部分都很好.

它停在这条线上：

var filteredContacts = dc.EAContactLists.Where(o => teams.Contains(o.Team)).ToList();

我迷失在这一个.