id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
26777	Cannot add foreign key constraint when migrating manytomany field	Ville Säävuori	nobody	"I have a model that looks like

{{{#!python
class LiveEvent(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    ...
    attendees = models.ManyToManyField(
        User, blank=True, related_name=""events_attended""
    )
    ...
    notify_subscriptions = models.ManyToManyField(
        User, blank=True, related_name=""events_subscribed""
    )
}}}

when trying to add and migrate notify_subscriptions field I get the following error:
{{{
django.db.utils.IntegrityError: (1215, 'Cannot add foreign key constraint')`
}}}

When adding 

{{{#!python
'OPTIONS': {
    ""init_command"": ""SET foreign_key_checks = 0;"",
},
}}}

to database settings , the error became: 

{{{
django.db.utils.OperationalError: (1825, ""Failed to add the foreign key constraint on table 'levan_liveevent_notify_subscriptions'. Incorrect options in FOREIGN KEY constraint 'slipmat/levan_liveevent_noti_liveevent_id_a4871abc_fk_levan_liveevent_id'"")
}}}

the migration file looks like:

{{{#!python
operations = [
    migrations.AddField(
        model_name='liveevent',
        name='notify_subscriptions',
        field=models.ManyToManyField(
            blank=True, related_name='events_subscribed', to=settings.AUTH_USER_MODEL
        ),
    ),
]
}}}

I'm using MySQL version 5.6.27 and Django version 1.9.7"	Bug	closed	Migrations	1.9	Normal	needsinfo			Unreviewed	0	0	0	0	0	0