Why do I get sqlite error, "unable to open database file"?

Using my Django app, I'm able to read from the database just fine. When the application didn't have permission to access the file, it gave me this error:

attempt to write a readonly database

Which made sense. So I edited the permissions on the file, so that the Apache process had write permissions. However, instead of it being able to write, I get this cryptic error:

unable to open database file

If it's useful, here's the entire output:

Request Method: POST
Request URL:    http://home-sv-1/hellodjango1/polls/1/vote/
Exception Type: OperationalError
Exception Value:    
unable to open database file
Exception Location: /usr/lib/pymodules/python2.5/django/db/backends/sqlite3/base.py in execute, line 193
Python Executable:  /usr/bin/python
Python Version: 2.5.2
Python Path:    ['/var/www', '/usr/lib/python2.5', '/usr/lib/python2.5/plat-linux2', '/usr/lib/python2.5/lib-tk', '/usr/lib/python2.5/lib-dynload', '/usr/local/lib/python2.5/site-packages', '/usr/lib/python2.5/site-packages', '/usr/lib/pymodules/python2.5', '/usr/lib/pymodules/python2.5/gtk-2.0']
Server time:    Sun, 23 Aug 2009 07:06:08 -0500

Let me know if a stack trace is necessary.

Aha, just stumbled across an article explaining this. Also Django have info on their NewbieMistakes page.

The solution is to make sure the directory containing the database file also has write access allowed to the process.

In my case, running this command fixed the problem:

sudo chown www-data .

My solution to this was more like so. I didn't really want to change the ownership of this dir. (mostly because i use the pi user to do things like git)

/var/www/mysite $ ls -la sql*
-rw-rw-r-- 1 pi       pi       25600 Jan  2 22:57 sqlite.db

(or whatever db you are using)

where pi is the user that i created all the files in. (yes this is a raspberry pi)

Instead of changing of permissions to www-data, i found that I only needed to change the permissions like this:

sudo chmod 775 /var/www/mysite
sudo chmod 664 /var/www/mysite/sqlite.db
sudo usermod -a -G pi www-data

This gives group write access to the necessary files and adds the www-data user to the pi group.

Note: if you have logging, you will need to do this for the django logfile as well or apache won't like it much.

From the Django says "Unable to Open Database File" when using SQLite3 section of the Newbie mistakes Django wiki page:

1. make sure Apache can also write to the parent directory of the database
2. make sure none of the folders of the database file's full path start with a number
3. make sure the full path to the db directory exists
4. make sure your /tmp directory is world-writable
5. make sure the path to the database specified in settings.py is a full path
6. make sure there are no special characters in the path
7. on Windows, make sure the db directory path is written with double backslashes

Adding an operational user to the www-data group is working well on my test environment. Additionally I've put the sqlite3.db file into a separate subfolder, to be more secure.

Database file shall be owned by www-data

sudo chown www-data mysite/db_sqlite3/
sudo chown www-data mysite/db_sqlite3/my.db

My operational user hape gets a member of www-data group:

sudo usermod -a -G www-data hape

Allow database file write access to members of group www-data:

sudo chmod u+w+x,g+w+x mysite/db_sqlite3/
sudo chmod u+w+x,g+w+x mysite/db_sqlite3/my.db

As a result, the database can be accessed read+write by apache2-daemon (user www-data), without giving grant to the project root folder, and - on the other hand - the app can be run in dev mode by the operational user hape, e.g.

./manage.py runserver

also.