Body: <p>1) Updated existing Craft 2 from the Control Panel</p>
  
  <p>2) <code>.env</code></p>
  
  <pre><code>DB_DRIVER="mysql"
  DB_SERVER="localhost"
  DB_USER="root"
  DB_PASSWORD="pwd"
  DB_DATABASE="dbname"
  DB_SCHEMA="public"
  DB_TABLE_PREFIX="some_"
  DB_PORT=""
  </code></pre>
  
  <p>3 ) <code>/var/www/html/somename/config/general.php</code></p>
  
  <pre><code>&lt;?php
  
  return [
      // Global settings
      '*' =&gt; [
          'defaultWeekStartDay' =&gt; 1,
  
          'omitScriptNameInUrls' =&gt; true,
  
          'cpTrigger' =&gt; 'admin',
  
          'securityKey' =&gt; getenv('SECURITY_KEY'),
  
  
          'useProjectConfigFile' =&gt; true,
      ],
      // Dev environment settings
      'dev' =&gt; [
          'devMode' =&gt; true,
          'useCompressedJs' =&gt; false,
          'allowUpdates' =&gt; true,
          'environmentVariables' =&gt; [
              'basePath' =&gt; '/var/www/html/craftcms3/web/',
              'baseUrl'  =&gt; 'http://craftcms3.local/',
          ],
          'siteUrl' =&gt; 'http://craftcms3.local/',
      ],
  
      // Staging environment settings
      'staging' =&gt; [
          // Prevent administrative changes from being made on staging
          'allowAdminChanges' =&gt; false,
      ],
  
      // Production environment settings
      'production' =&gt; [
          // Prevent administrative changes from being made on production
          'allowAdminChanges' =&gt; false,
      ],
  ];
  </code></pre>
  
  <p>4) and followed other mentioned steps at <a href="https://docs.craftcms.com/v3/upgrade.html#performing-the-upgrade" rel="nofollow noreferrer">https://docs.craftcms.com/v3/upgrade.html#performing-the-upgrade</a> </p>
  
  <blockquote>
    <p>Permission at root:</p>
  </blockquote>
  
  <pre><code>sudo chown www-data:www-data  -R *
  sudo find . -type d -exec chmod 755 {} \;
  sudo find . -type f -exec chmod 644 {} \;
  </code></pre>
  
  <p>Error when I hit <a href="http://craftcms3.local/admin" rel="nofollow noreferrer">http://craftcms3.local/admin</a> </p>
  
  <pre><code>craft\web\ServiceUnavailableHttpException in /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php:689
  Stack trace:
  #0 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php(223): craft\web\Application-&gt;_processUpdateLogic(Object(craft\web\Request))
  #1 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/Application.php(386): craft\web\Application-&gt;handleRequest(Object(craft\web\Request))
  #2 /var/www/html/craftcms3/web/index.php(22): yii\base\Application-&gt;run()
  #3 {main}
  </code></pre>
  
  <blockquote>
    <p>Till now I haven't installed any plugins in Craft 3</p>
  </blockquote>
  
  <p>Update: </p>
  
  <p>I tried again by following all steps above got the DB UPDATE screen after long time my system freezes now i got this error.</p>
  
  <pre><code>Database Exception: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'locale' in 'craft_categorygroups_i18n'
  The SQL being executed was: ALTER TABLE `craft_categorygroups_i18n` ADD `siteId` int(11) AFTER `locale`
  
  Migration: craft\migrations\m160807_144858_sites
  
  Output:
  
  &gt; execute SQL: SET FOREIGN_KEY_CHECKS = 0 ... done (time: 0.000s)
  &gt; dropping {{%sites}} if it exists ... done (time: 0.271s)
  &gt; create table {{%sites}} ... done (time: 0.385s)
  &gt; create unique index craft_sites_handle_unq_idx on {{%sites}} (handle) ... done (time: 0.343s)
  &gt; create index craft_sites_sortOrder_idx on {{%sites}} (sortOrder) ... done (time: 0.284s)
  &gt; insert into {{%sites}} ... done (time: 0.041s)
  &gt; update in {{%userpermissions}} ... done (time: 0.004s)
  &gt; add column siteId integer AFTER `locale` to table {{%categorygroups_i18n}} ...Exception: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'locale' in 'craft_categorygroups_i18n'
  The SQL being executed was: ALTER TABLE `craft_categorygroups_i18n` ADD `siteId` int(11) AFTER `locale` (/var/www/html/craftcms3/vendor/yiisoft/yii2/db/Schema.php:664)
  #0 /var/www/html/craftcms3/vendor/yiisoft/yii2/db/Command.php(1295): yii\db\Schema-&gt;convertException(Object(PDOException), 'ALTER TABLE `cr...')
  #1 /var/www/html/craftcms3/vendor/yiisoft/yii2/db/Command.php(1091): yii\db\Command-&gt;internalExecute('ALTER TABLE `cr...')
  #2 /var/www/html/craftcms3/vendor/yiisoft/yii2/db/Migration.php(377): yii\db\Command-&gt;execute()
  #3 /var/www/html/craftcms3/vendor/craftcms/cms/src/migrations/m160807_144858_sites.php(547): yii\db\Migration-&gt;addColumn('{{%categorygrou...', 'siteId', Object(craft\db\mysql\ColumnSchemaBuilder))
  #4 /var/www/html/craftcms3/vendor/craftcms/cms/src/migrations/m160807_144858_sites.php(150): craft\migrations\m160807_144858_sites-&gt;addSiteColumn('{{%categorygrou...', 'siteId', true, 'locale')
  #5 /var/www/html/craftcms3/vendor/craftcms/cms/src/db/Migration.php(56): craft\migrations\m160807_144858_sites-&gt;safeUp()
  #6 /var/www/html/craftcms3/vendor/craftcms/cms/src/db/MigrationManager.php(243): craft\db\Migration-&gt;up(true)
  #7 /var/www/html/craftcms3/vendor/craftcms/cms/src/db/MigrationManager.php(163): craft\db\MigrationManager-&gt;migrateUp(Object(craft\migrations\m160807_144858_sites))
  #8 /var/www/html/craftcms3/vendor/craftcms/cms/src/services/Updates.php(215): craft\db\MigrationManager-&gt;up()
  #9 /var/www/html/craftcms3/vendor/craftcms/cms/src/controllers/BaseUpdaterController.php(521): craft\services\Updates-&gt;runMigrations(Array)
  #10 /var/www/html/craftcms3/vendor/craftcms/cms/src/controllers/UpdaterController.php(209): craft\controllers\BaseUpdaterController-&gt;runMigrations(Array, 'restore-db')
  #11 [internal function]: craft\controllers\UpdaterController-&gt;actionMigrate()
  #12 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/InlineAction.php(57): call_user_func_array(Array, Array)
  #13 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/Controller.php(157): yii\base\InlineAction-&gt;runWithParams(Array)
  #14 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Controller.php(109): yii\base\Controller-&gt;runAction('migrate', Array)
  #15 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/Module.php(528): craft\web\Controller-&gt;runAction('migrate', Array)
  #16 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php(297): yii\base\Module-&gt;runAction('updater/migrate', Array)
  #17 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php(683): craft\web\Application-&gt;runAction('updater/migrate')
  #18 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php(223): craft\web\Application-&gt;_processUpdateLogic(Object(craft\web\Request))
  #19 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/Application.php(386): craft\web\Application-&gt;handleRequest(Object(craft\web\Request))
  #20 /var/www/html/craftcms3/web/index.php(22): yii\base\Application-&gt;run()
  #21 {main}
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2019-03-06T14:36:53.543Z
Comments.Text: Have you looked at the `web.log` file in `storage/logs/` for more details on why the error is happening? A 503 error could be because Craft is unable to connect to your database, for example.
Comments.UserDisplayName: Martin Spain
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2019-03-06T15:50:23.647Z
Comments.Text: You should ad the db port as well. This is 99% a db connection problem.
  Do you need to make an ssl connection to your db? that's what I ran into.
Comments.UserDisplayName: KSPR
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2019-03-06T15:59:20.293Z
Comments.Text: I am doing this on my localhost, Currently i don't have access to my system, will add the available port and check. and suggested below i will check the log as well if it exists.
Comments.UserDisplayName: inrsaurabh
Tags: <craft3><upgrades>
Title: Got HTTP 503 – Service Unavailable error while updating to Craft 3
ThreadText: # Got HTTP 503 – Service Unavailable error while updating to Craft 3
  
  (Asked by: username_0 on 2019-03-06)
  
  1) Updated existing Craft 2 from the Control Panel
  
  2) `.env`
  
  ```
  DB_DRIVER="mysql"
  DB_SERVER="localhost"
  DB_USER="root"
  DB_PASSWORD="pwd"
  DB_DATABASE="dbname"
  DB_SCHEMA="public"
  DB_TABLE_PREFIX="some_"
  DB_PORT=""
  
  ```
  
  3 ) `/var/www/html/somename/config/general.php`
  
  ```
  <?php
  
  return [
      // Global settings
      '*' => [
          'defaultWeekStartDay' => 1,
  
          'omitScriptNameInUrls' => true,
  
          'cpTrigger' => 'admin',
  
          'securityKey' => getenv('SECURITY_KEY'),
  
          'useProjectConfigFile' => true,
      ],
      // Dev environment settings
      'dev' => [
          'devMode' => true,
          'useCompressedJs' => false,
          'allowUpdates' => true,
          'environmentVariables' => [
              'basePath' => '/var/www/html/craftcms3/web/',
              'baseUrl'  => 'http://craftcms3.local/',
          ],
          'siteUrl' => 'http://craftcms3.local/',
      ],
  
      // Staging environment settings
      'staging' => [
          // Prevent administrative changes from being made on staging
          'allowAdminChanges' => false,
      ],
  
      // Production environment settings
      'production' => [
          // Prevent administrative changes from being made on production
          'allowAdminChanges' => false,
      ],
  ];
  
  ```
  
  4) and followed other mentioned steps at <https://docs.craftcms.com/v3/upgrade.html#performing-the-upgrade>
  
  > Permission at root:
  
  ```
  sudo chown www-data:www-data  -R *
  sudo find . -type d -exec chmod 755 {} \;
  sudo find . -type f -exec chmod 644 {} \;
  
  ```
  
  Error when I hit <http://craftcms3.local/admin>
  
  ```
  craft\web\ServiceUnavailableHttpException in /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php:689
  Stack trace:
  #0 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php(223): craft\web\Application->_processUpdateLogic(Object(craft\web\Request))
  #1 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/Application.php(386): craft\web\Application->handleRequest(Object(craft\web\Request))
  #2 /var/www/html/craftcms3/web/index.php(22): yii\base\Application->run()
  #3 {main}
  
  ```
  
  > Till now I haven't installed any plugins in Craft 3
  
  Update:
  
  I tried again by following all steps above got the DB UPDATE screen after long time my system freezes now i got this error.
  
  ```
  Database Exception: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'locale' in 'craft_categorygroups_i18n'
  The SQL being executed was: ALTER TABLE `craft_categorygroups_i18n` ADD `siteId` int(11) AFTER `locale`
  
  Migration: craft\migrations\m160807_144858_sites
  
  Output:
  
  > execute SQL: SET FOREIGN_KEY_CHECKS = 0 ... done (time: 0.000s)
  > dropping {{%sites}} if it exists ... done (time: 0.271s)
  > create table {{%sites}} ... done (time: 0.385s)
  > create unique index craft_sites_handle_unq_idx on {{%sites}} (handle) ... done (time: 0.343s)
  > create index craft_sites_sortOrder_idx on {{%sites}} (sortOrder) ... done (time: 0.284s)
  > insert into {{%sites}} ... done (time: 0.041s)
  > update in {{%userpermissions}} ... done (time: 0.004s)
  > add column siteId integer AFTER `locale` to table {{%categorygroups_i18n}} ...Exception: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'locale' in 'craft_categorygroups_i18n'
  The SQL being executed was: ALTER TABLE `craft_categorygroups_i18n` ADD `siteId` int(11) AFTER `locale` (/var/www/html/craftcms3/vendor/yiisoft/yii2/db/Schema.php:664)
  #0 /var/www/html/craftcms3/vendor/yiisoft/yii2/db/Command.php(1295): yii\db\Schema->convertException(Object(PDOException), 'ALTER TABLE `cr...')
  #1 /var/www/html/craftcms3/vendor/yiisoft/yii2/db/Command.php(1091): yii\db\Command->internalExecute('ALTER TABLE `cr...')
  #2 /var/www/html/craftcms3/vendor/yiisoft/yii2/db/Migration.php(377): yii\db\Command->execute()
  #3 /var/www/html/craftcms3/vendor/craftcms/cms/src/migrations/m160807_144858_sites.php(547): yii\db\Migration->addColumn('{{%categorygrou...', 'siteId', Object(craft\db\mysql\ColumnSchemaBuilder))
  #4 /var/www/html/craftcms3/vendor/craftcms/cms/src/migrations/m160807_144858_sites.php(150): craft\migrations\m160807_144858_sites->addSiteColumn('{{%categorygrou...', 'siteId', true, 'locale')
  #5 /var/www/html/craftcms3/vendor/craftcms/cms/src/db/Migration.php(56): craft\migrations\m160807_144858_sites->safeUp()
  #6 /var/www/html/craftcms3/vendor/craftcms/cms/src/db/MigrationManager.php(243): craft\db\Migration->up(true)
  #7 /var/www/html/craftcms3/vendor/craftcms/cms/src/db/MigrationManager.php(163): craft\db\MigrationManager->migrateUp(Object(craft\migrations\m160807_144858_sites))
  #8 /var/www/html/craftcms3/vendor/craftcms/cms/src/services/Updates.php(215): craft\db\MigrationManager->up()
  #9 /var/www/html/craftcms3/vendor/craftcms/cms/src/controllers/BaseUpdaterController.php(521): craft\services\Updates->runMigrations(Array)
  #10 /var/www/html/craftcms3/vendor/craftcms/cms/src/controllers/UpdaterController.php(209): craft\controllers\BaseUpdaterController->runMigrations(Array, 'restore-db')
  #11 [internal function]: craft\controllers\UpdaterController->actionMigrate()
  #12 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/InlineAction.php(57): call_user_func_array(Array, Array)
  #13 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/Controller.php(157): yii\base\InlineAction->runWithParams(Array)
  #14 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Controller.php(109): yii\base\Controller->runAction('migrate', Array)
  #15 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/Module.php(528): craft\web\Controller->runAction('migrate', Array)
  #16 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php(297): yii\base\Module->runAction('updater/migrate', Array)
  #17 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php(683): craft\web\Application->runAction('updater/migrate')
  #18 /var/www/html/craftcms3/vendor/craftcms/cms/src/web/Application.php(223): craft\web\Application->_processUpdateLogic(Object(craft\web\Request))
  #19 /var/www/html/craftcms3/vendor/yiisoft/yii2/base/Application.php(386): craft\web\Application->handleRequest(Object(craft\web\Request))
  #20 /var/www/html/craftcms3/web/index.php(22): yii\base\Application->run()
  #21 {main}
  
  ```
  
  **Tags:** craft3, upgrades
  
  > **Comments:**
  > **username_1**: Have you looked at the `web.log` file in `storage/logs/` for more details on why the error is happening? A 503 error could be because Craft is unable to connect to your database, for example.  
  > **username_2**: You should ad the db port as well. This is 99% a db connection problem. Do you need to make an ssl connection to your db? that's what I ran into.  
  > **username_0**: I am doing this on my localhost, Currently i don't have access to my system, will add the available port and check. and suggested below i will check the log as well if it exists.  
  
  ---
  
  ## 0 answers
  
  