There are no commands defined in the "cron" namespace.

[woei66]

based on the doc
http://devdocs.magento.com/guides/v2.0/config-guide/cli/config-cli-subcommands-cron.html
I setup the cron and execute on cli
php /path/magento2/bin/magento cron:run
but I got an error message
[InvalidArgumentException]
There are no commands defined in the "cron" namespace.

[dmitrii-fediuk]

How to fix the «There are no commands defined» failure while executing a console command

[mazhalai]

@woei66 please use the -v or -vv option in the command line for more details to see what exactly is causing this error.

[nkarthickannan]

@woei66

I was also facing the similar issue. Issuing sudo chmod -R 777 * in my Ubuntu system solves this issue. It seems Magento is not able to create classes under var/generation directory. I am not sure what directory permission should be given to avoid this problem

[stepzerosolutions]

This could be due to composer.json file in your module or theme. I've got the same issue

[InvalidArgumentException]
There are no commands defined in the "setup" namespace.

remove the composer file and run the command and it will update the module.

@woei66 Your issue is likely with permissions and ownership. See this page for more info.

[woei66]

@stepzerosolutions
remove the composer file doesn't fix the probelm

@mazhalai here is the -vv output
Exception trace:
() at /xxx/magento2/vendor/symfony/console/Symfony/Component/Console/Application.php:501
Symfony\Component\Console\Application->findNamespace() at /xxx/magento2/vendor/symfony/console/Symfony/Component/Console/Application.php:535
Symfony\Component\Console\Application->find() at /xxx/magento2/vendor/symfony/console/Symfony/Component/Console/Application.php:192
Symfony\Component\Console\Application->doRun() at /xxx/magento2/lib/internal/Magento/Framework/Console/Cli.php:49
Magento\Framework\Console\Cli->doRun() at /xxx/magento2/vendor/symfony/console/Symfony/Component/Console/Application.php:126
Symfony\Component\Console\Application->run() at /xxx/magento2/bin/magento:25

@karthickannan
You are right. The problem is the permission.
I try to execute the command with root permission and traced which directories and files are generated/modified.
Here are the output
./var/cache/mage--b/mage---064_CRONTAB__EVENT_CONFIG_CACHE
./var/cache/mage--b/mage---064_CRONTAB_CONFIG_CACHE
./var/cache/mage--7/mage---064_DB_PDO_MYSQL_DDL_CRON_SCHEDULE_1
./var/cache/mage--e/mage---064_CRON_LAST_SCHEDULE_GENERATE_ATDEFAULT
./var/cache/mage--9/mage---064_RESOLVED_STORES_D7A094A061F9E5121D10DBCA79ABB6E0
./var/cache/mage--3/mage---064_CRON_LAST_HISTORY_CLEANUP_ATINDEX
./var/cache/mage--0/mage---064_CRON_LAST_HISTORY_CLEANUP_ATDEFAULT
./var/cache/mage--0/mage---064_CRONTAB__RESOURCESCACHE
./var/cache/mage--c/mage---064_GLOBAL_CRONTAB_PLUGIN_LIST
./var/cache/mage--1/mage---064_CRON_LAST_SCHEDULE_GENERATE_ATINDEX

So, to fix the problem is simple, just make sure the cron account has the permission to write data to var/cache permission.

I think:

1. the error message is not clear and user can't figure out the problem easily
2. the -vv doesn't display enough information since it's a permission, I didn't see the permission warning on this.

[woei66]

the next question is: where is the check point for the permission checking?
at the check point, it should throw a exception that the cron owner has no enough permission to write the directory.

[woei66]

What I did:

1. using root to execute "php bin/magento cron:run"
2. using "find ./ -mmin -60" to know which files or directories are modified
3. It displayed that some files are generated at the "var/cache/" directory
4. I knew that the account which execute the "php bin/magento cron:run" without enough permission to write data to the "var/cache/" directory
5. I need to add permission to the account and it can write the "var/cache/" directory

[nkarthickannan]

@woei66

Hi,

Please check if this document helps to resolve this problem http://devdocs.magento.com/guides/v2.0/install-gde/prereq/apache-user.html

I'll check this procedure and update here if it solves this problem.

Thanks

[nkarthickannan]

@woei66

In my opinion, running the CLI commands as root user will create more problems. Because the Cache files will be generated as root user. Hence you may face problems while removing the cache files. So, never run the CLI commands as root user. Instead use the sudo (if it is Ubuntu) for authorization.

Thanks

[nkarthickannan]

@woei66

The following commands helped for me to install Magento 2 with sample data

Magento 2 installation with sample data

1. cd /var/www
2. composer create-project --repository-url=https://repo.magento.com/ magento/project-community-edition mage2
3. ps aux | grep apache
4. groups www-data
5. groups <my_user_name> (<my_user_name> is already in the primary group of www-data)
6. sudo service apache2 restart
7. cd mage2
8. sudo chown -R :www-data .
9. sudo find . -type d -exec chmod 770 {} ; && sudo find . -type f -exec chmod 660 {} ; && sudo chmod u+x bin/magento
10. bin/magento sampledata:deploy
11. composer update
12. bin/magento setup:upgrade
13. sudo chown -R :www-data .

I'm using LAMP stack in Ubuntu 14.04. Please check these and let me know the result.

Thanks

[katmoon]

Internal ticket MAGETWO-49955 is created for this issue.
Thanks everyone for your input.