The website encountered an unexpected error. Please try again later.

By donm on 7 Jan 2018 at 06:24 UTC

Under Drupal 8.4.4; UniserverZ version 13 WAMP stack (PHP 7.1). After upgrade from D7 to D8, using the Migrate UI path. I might have more than one problem:

1. First up is the "unexpected error" issue -- which from other threads arises because Apache runs into some kind of trouble before Drupal loads. The error arises only when I try to access the "Extend" tab on the administrative menu (ie, I have no access to the module control); I can access other parts of Drupal as per normal. I have tried manually clearing (truncating) all cache tables in the database (thru PhpMyAdmin), but the error persists.

The screen shows this further message:

Drupal\Component\Plugin\Exception\PluginNotFoundException</em>: The &quot;migrate_example_advanced_position&quot; plugin does not exist. in <em class="placeholder">Drupal\Core\Plugin\DefaultPluginManager-&gt;doGetDefinition()</em> (line <em class="placeholder">52</em> of <em class="placeholder">core\lib\Drupal\Component\Plugin\Discovery\DiscoveryTrait.php</em>).

And the Apache error log shows this:

[Sat Jan 06 21:47:18.531230 2018] [php7:notice] [pid 4984:tid 1944] [client 127.0.0.1:52093] Uncaught PHP Exception Drupal\\Component\\Plugin\\Exception\\PluginNotFoundException: "The "migrate_example_advanced_position" plugin does not exist." at \\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Component\\Plugin\\Discovery\\DiscoveryTrait.php line 52, referer: http://d8dev.incorporate.dd/admin/config

1A. Running update.php (before clearing the caches) also produced the "unexpected error" message (upon pressing the final "continue" button). After clearing the caches, the error is still there, but the HTML is now correctly formatted:

The website encountered an unexpected error. Please try again later.
Drupal\Component\Plugin\Exception\PluginNotFoundException: The "migrate_example_advanced_position" plugin does not exist. in Drupal\Core\Plugin\DefaultPluginManager->doGetDefinition() (line 52 of core\lib\Drupal\Component\Plugin\Discovery\DiscoveryTrait.php).

I'm not sure why Drupal won't re-initialize the modules (ie, focus on what it does have instead of pining for what is gone -- the issue reminds me of the "missing modules message" fix that had to be issued for Drupal 7.50).

2. Probably related to the above issue are 7 warning messages about Drupal's bootstrap.inc not being able to find certain modules. (I did flush the bootstrap cache.) This warning appears when I click "Configuration" from the admin menu. I did use Drush to remove the bottom 3 modules, with Drush reporting success.

User warning: The following module is missing from the file system: migrate_example in drupal_get_filename() (line 250 of core\includes\bootstrap.inc).

User warning: The following module is missing from the file system: migrate_example_advanced in drupal_get_filename() (line 250 of core\includes\bootstrap.inc).

User warning: The following module is missing from the file system: migrate_example_advanced_setup in drupal_get_filename() (line 250 of core\includes\bootstrap.inc).

User warning: The following module is missing from the file system: migrate_example_setup in drupal_get_filename() (line 250 of core\includes\bootstrap.inc).

User warning: The following module is missing from the file system: migrate_plus in drupal_get_filename() (line 250 of core\includes\bootstrap.inc).

User warning: The following module is missing from the file system: migrate_tools in drupal_get_filename() (line 250 of core\includes\bootstrap.inc).

User warning: The following module is missing from the file system: migrate_upgrade in drupal_get_filename() (line 250 of core\includes\bootstrap.inc).

3. And the Apache error log after 1A is a long one, and says this:

[Sat Jan 06 22:13:56.945911 2018] [php7:notice] [pid 4984:tid 1884] [client 127.0.0.1:52377] Drupal\\Component\\Plugin\\Exception\\PluginNotFoundException: The "migrate_example_advanced_position" plugin does not exist. in C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Component\\Plugin\\Discovery\\DiscoveryTrait.php on line 52 #0 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Component\\Plugin\\Discovery\\DiscoveryCachedTrait.php(25): Drupal\\Core\\Plugin\\DefaultPluginManager->doGetDefinition(Array, 'migrate_example...', true)\n#1 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\Plugin\\Factory\\ContainerFactory.php(16): Drupal\\Core\\Plugin\\DefaultPluginManager->getDefinition('migrate_example...')\n#2 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Component\\Plugin\\PluginManagerBase.php(84): Drupal\\Core\\Plugin\\Factory\\ContainerFactory->createInstance('migrate_example...', Array)\n#3 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\Plugin\\DefaultSingleLazyPluginCollection.php(62): Drupal\\Component\\Plugin\\PluginManagerBase->createInstance('migrate_example...', Array)\n#4 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Component\\Plugin\\LazyPluginCollection.php(80): Drupal\\Core\\Plugin\\DefaultSingleLazyPluginCollection->initializePlugin('migrate_example...')\n#5 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\Plugin\\DefaultSingleLazyPluginCollection.php(83): Drupal\\Component\\Plugin\\LazyPluginCollection->get('migrate_example...')\n#6 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\Plugin\\DefaultSingleLazyPluginCollection.php(99): Drupal\\Core\\Plugin\\DefaultSingleLazyPluginCollection->setConfiguration(Array)\n#7 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\Plugin\\DefaultSingleLazyPluginCollection.php(55): Drupal\\Core\\Plugin\\DefaultSingleLazyPluginCollection->addInstanceId('migrate_example...', Array)\n#8 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\modules\\rest\\src\\Entity\\RestResourceConfig.php(206): Drupal\\Core\\Plugin\\DefaultSingleLazyPluginCollection->__construct(Object(Drupal\\rest\\Plugin\\Type\\ResourcePluginManager), 'migrate_example...', Array)\n#9 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\modules\\rest\\src\\Entity\\RestResourceConfig.php(111): Drupal\\rest\\Entity\\RestResourceConfig->getPluginCollections()\n#10 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\modules\\rest\\src\\Routing\\ResourceRoutes.php(88): Drupal\\rest\\Entity\\RestResourceConfig->getResourcePlugin()\n#11 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\modules\\rest\\src\\Routing\\ResourceRoutes.php(69): Drupal\\rest\\Routing\\ResourceRoutes->getRoutesForResourceConfig(Object(Drupal\\rest\\Entity\\RestResourceConfig))\n#12 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Component\\EventDispatcher\\ContainerAwareEventDispatcher.php(108): Drupal\\rest\\Routing\\ResourceRoutes->onDynamicRouteEvent(Object(Drupal\\Core\\Routing\\RouteBuildEvent), 'routing.route_d...', Object(Drupal\\Component\\EventDispatcher\\ContainerAwareEventDispatcher))\n#13 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\Routing\\RouteBuilder.php(179): Drupal\\Component\\EventDispatcher\\ContainerAwareEventDispatcher->dispatch('routing.route_d...', Object(Drupal\\Core\\Routing\\RouteBuildEvent))\n#14 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\ProxyClass\\Routing\\RouteBuilder.php(83): Drupal\\Core\\Routing\\RouteBuilder->rebuild()\n#15 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\includes\\common.inc(1157): Drupal\\Core\\ProxyClass\\Routing\\RouteBuilder->rebuild()\n#16 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\modules\\system\\src\\Controller\\DbUpdateController.php(350): drupal_flush_all_caches()\n#17 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\modules\\system\\src\\Controller\\DbUpdateController.php(164): Drupal\\system\\Controller\\DbUpdateController->selection(Object(Symfony\\Component\\HttpFoundation\\Request))\n#18 [internal function]: Drupal\\system\\Controller\\DbUpdateController->handle('selection', Object(Symfony\\Component\\HttpFoundation\\Request))\n#19 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\Update\\UpdateKernel.php(110): call_user_func_array(Array, Array)\n#20 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\core\\lib\\Drupal\\Core\\Update\\UpdateKernel.php(73): Drupal\\Core\\Update\\UpdateKernel->handleRaw(Object(Symfony\\Component\\HttpFoundation\\Request))\n#21 C:\\Users\\Owner\\Sites\\UniServerZ\\vhosts\\d8dev\\web\\update.php(28): Drupal\\Core\\Update\\UpdateKernel->handle(Object(Symfony\\Component\\HttpFoundation\\Request))\n#22 {main}, referer: http://d8dev.incorporate.dd/update.php?continue=1

Thanks for any replies.

Comments

Managed to get things working by editing database

donm commented 8 January 2018 at 05:31

I managed to fix the above problems by searching the database (using PhpMyAdmin) for the identified missing modules (from the Drupal listing) and deleting the applicable row. The reference for the first message was found in the "config" table and for the others in the "key value" and "key value expire" tables.

Making those changes also solved the trouble I had in accessing the "extend" tab (and also the "people" tab) in the admin menu.

any other solution

Sangeetha Kanneboina commented 25 October 2018 at 10:15

i am facing the same issue,is there any solution,apart from deleting from database

"Extend" tab only error message

ynes commented 23 July 2019 at 14:12

Just installed Drupal 8 on two new brand sites yesterday. Like the OP, now when I click on the "Extend" menu tab only, I get a blank screen with this error message.

Bizzarely, this error only happens on the site I have done nothing with yet.

One error message from the log is this. What can I do?

Drupal\Core\Extension\Exception\UnknownExtensionException: The module standard does not exist. in Drupal\Core\Extension\ExtensionList->get() (line 257 of /homepages/15/d792024322/htdocs/clickandbuilds/Drupal/ABA-CMS/core/lib/Drupal/Core/Extension/ExtensionList.php).