# 3.5.4. Troubleshooting Analytics Devstack Installation¶

This section provides information about problems that you might encounter when using Open edX virtual machines (VMs). Open edX VMs are devstack, fullstack, or analytics devstack installations.

## 3.5.4.1. Time out Error While Creating an Open edX VM¶

In some cases, you might see a time out error when you attempt to create an edX VM. For example, you might see the following error message during a virtual machine installation.

mount.nfs: mount to NFS server '192.168.33.1:/path/to/edx-platform' failed:
timed out, giving up


This error happens because the Vagrant virtual machine software that is used by devstack and fullstack cannot create a host-only network while the host computer (for example, your laptop) is connected to a virtual private network (VPN). The Vagrant software can only create the network required by devstack and fullstack while your VPN software is disconnected. Be sure to disconnect your VPN before you attempt to install devstack or fullstack.

To correct the error, follow these steps.

1. Stop any VPNs that are active on the host computer.
2. Enter vagrant halt on the command line from the installation directory of your devstack or fullstack environment.
3. Start the Oracle Virtualbox program if it is not running.
4. In Virtualbox, choose Preferences > Network > Host-only Networks and remove the host-only network that was most recently created.
5. Enter vagrant up on the command line.

## 3.5.4.2. Starting Open edX Servers after a MongoDB Failure¶

If you do not stop Open edX servers such as the LMS before halting the Vagrant VM that they are running on, the server leaves a MongoDB® database lock file in place. This lock file will prevent the Open edX server from starting MongoDB when you try to start the server again.

The following error message appears in the console when this problem occurs.

File "/edx/app/edxapp/venvs/edxapp/local/lib/python2.7/site-
packages/pymongo/mongo_client.py", line 425, in __init__ raise
ConnectionFailure(str(e)) pymongo.errors.ConnectionFailure: [Errno 111]
Connection refused


Invoke the following commands as the vagrant user on the VM to remove the MongoDB lock file, restore its configuration, and start the database service. After you invoke these commands, you can start the Open edX server again.

sudo rm /edx/var/mongo/mongodb/mongod.lock
sudo mongod -repair --config /etc/mongod.conf
sudo chown -R mongodb:mongodb /edx/var/mongo/.
sudo service mongod start