'ValidationError' object has no attribute 'error_dict' when creating a network

Bug #1299114 reported by Dimiter Naydenov on 2014-03-28
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Jeroen T. Vermeulen

Bug Description

I can't add a network either through the web UI or using the maas CLI. I'm getting this exception:

AttributeError: 'ValidationError' object has no attribute 'error_dict'

I can edit or delete an existing network OK, just can't add.

I'm running MAAS 1.5 r2188 from the daily ppa, on trusty, upgraded from precise.
I have installed maas (both RC and CC) on a KVM amd64 machine with 20GB disk and 1GB RAM. I also have 4 enlisted nodes (in Ready state), also KVM based.

Output from dpkg -l '*maas*'|cat:

Contents of /var/log/maas/* is attached.

Related branches

Dimiter Naydenov (dimitern) wrote :
Gavin Panella (allenap) on 2014-03-28
Changed in maas:
status: New → Triaged
importance: Undecided → Critical
Gavin Panella (allenap) wrote :

Dimiter, I can't reproduce this. Can you check that all dependencies on the machine are up-to-date?

Dimiter Naydenov (dimitern) wrote :

I did apt-get update & upgrade and still get the same issue. Did some search for this issue in django (v1.6.1) bugs, but nothing definite. What info will be useful? I suppose I can try uploading the machine and its disk image to U1 so you can try it, along with the setup that's needed..

Gavin Panella (allenap) wrote :

Uploading the disk image sounds like a pain, but it would be massively useful.

Dimiter Naydenov (dimitern) wrote :

I'm preparing the upload and will post links as it's done.

I took me 3h just to tar.bz2 the disk image (21GB down to around 10GB).

Raphaël Badin (rvb) wrote :

Can't reproduced this either. Using a dev instance, I ran the command Dimiter gave me and it didn't crash:
$ ./bin/maas maas networks create name=main ip= netmask= description="Main MAAS network"
    "description": "Main MAAS network",
    "ip": "",
    "netmask": "",
    "vlan_tag": null,
    "resource_uri": "/api/1.0/networks/main/",
    "name": "main"

Dimiter Naydenov (dimitern) wrote :

I gave up trying to upload that 8.5GB image to U1.

However, I managed to find a probable cause:

As you can see, before trying to add "main" I had 2 networks - "net1" ( and "vlan0" ( The cluster controller has 3 NICs: 1 unmanaged and unconfigured (lo), 1 managed (dhcp+dns) (eth0) and another managed (dhcp+dns) (eth1). Trying to add a new "main" network with the same IP (network) address fails with the above error. I successfully added a "main1" with the same net address, but a different subnet (, but failed adding it before changing the name (it said {"name": ["Network with this Name already exists."]}).

So it seems the validation error is correct, but not user-friendly :)

Jeroen T. Vermeulen (jtv) wrote :

In theory we do not allow multiple networks with overlapping (i.e. identical or nested) address ranges. In the model code, Network.validate_unique checks against such clashes, and raises a ValidationError. Maybe this needs to be a different, more specific error; or maybe the form code needs to catch the ValidationError and attach the error to a specific field.

Jeroen T. Vermeulen (jtv) wrote :

Got it. This doesn't become clear in the documentation as far as I can see, and even runs counter to the examples, but when validate_unique raises a ValidationError, it has to be one that was constructed from a messages dict! If not, kaboom inside Django.

Changed in maas:
assignee: nobody → Jeroen T. Vermeulen (jtv)
status: Triaged → In Progress
Changed in maas:
status: In Progress → Fix Committed
Changed in maas:
status: Fix Committed → Fix Released
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