Migration: MSSQL - dropColumn causing problems

Hello there,

In my migrate-up script I’m doing

$this->addColumn('USER', 'AUTH_KEY', $this->string(32)->notNull()->defaultValue('-'));

which runs through,

but when migrating down,

 $this->dropColumn('USER', 'AUTH_KEY');

it doesn’t work with the following errormsg from mssql:

[2] => [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]Das Objekt-Objekt ‘DF__USER__AUTH_KE__147C05D0’ ist vom Spalte-Objekt ‘AUTH_KEY’ abh├ñngig.

meaning sth. like "the object ‘DF__USER__AUTH_KE__147C05D0’ depends on the row-object ‘AUTH_KEY’.

Is there any configuration I can make which allows to remove associated objects like default values?