Uncaught exception thrown in session handler.

Drupal\Core\Database\DatabaseExceptionWrapper: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT 1 AS expression FROM {sessions} sessions WHERE sid = :db_condition_placeholder_0; Array ( [:db_condition_placeholder_0] => t_s1VcKh50G8tetKzlmr_sR_00F0O-RNoFf6ArqYGRc ) in Drupal\Core\Session\SessionHandler->write() (line 84 of /var/www/html/new_trainee/core/lib/Drupal/Core/Session/SessionHandler.php).

Drupal\Core\Session\SessionHandler->write('93wVS4aLQD9mKwelI-o-GmXNbB0Qs3zFuoBDQJUEHOk', '_symfony_flashes|a:1:{s:5:"error";a:1:{i:0;O:25:"Drupal\Core\Render\Markup":1:{s:9:"*string";s:2733:"<em class="placeholder">Warning</em>: Error while sending QUERY packet. PID=14837 in <em class="placeholder">Drupal\Core\Database\Statement-&gt;execute()</em> (line <em class="placeholder">59</em> of <em class="placeholder">core/lib/Drupal/Core/Database/Statement.php</em>). Drupal\Core\Database\Statement-&gt;execute(Array, Array) (Line: 631)
Drupal\Core\Database\Connection-&gt;query(&#039;SELECT cid, data, created, expire, serialized, tags, checksum FROM {cache_discovery} WHERE cid IN ( :cids__0 ) ORDER BY cid&#039;, Array, Array) (Line: 358)
Drupal\Core\Database\Driver\mysql\Connection-&gt;query(&#039;SELECT cid, data, created, expire, serialized, tags, checksum FROM {cache_discovery} WHERE cid IN ( :cids[] ) ORDER BY cid&#039;, Array) (Line: 113)
Drupal\Core\Cache\DatabaseBackend-&gt;getMultiple(Array, ) (Line: 92)
Drupal\Core\Cache\DatabaseBackend-&gt;get(&#039;variant_plugins&#039;) (Line: 37)
Drupal\Core\Plugin\DefaultPluginManager-&gt;cacheGet(&#039;variant_plugins&#039;) (Line: 207)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getCachedDefinitions() (Line: 173)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getDefinitions() (Line: 22)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getDefinition(&#039;block_page&#039;) (Line: 16)
Drupal\Core\Plugin\Factory\ContainerFactory-&gt;createInstance(&#039;block_page&#039;, Array) (Line: 83)
Drupal\Component\Plugin\PluginManagerBase-&gt;createInstance(&#039;block_page&#039;) (Line: 236)
Drupal\Core\Render\MainContent\HtmlRenderer-&gt;prepare(Array, Object, Object) (Line: 117)
Drupal\Core\Render\MainContent\HtmlRenderer-&gt;renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber-&gt;onViewRenderArray(Object, &#039;kernel.view&#039;, Object)
call_user_func(Array, Object, &#039;kernel.view&#039;, Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher-&gt;dispatch(&#039;kernel.view&#039;, Object) (Line: 156)
Symfony\Component\HttpKernel\HttpKernel-&gt;handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel-&gt;handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session-&gt;handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle-&gt;handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache-&gt;pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache-&gt;handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware-&gt;handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware-&gt;handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel-&gt;handle(Object, 1, 1) (Line: 693)
Drupal\Core\DrupalKernel-&gt;handle(Object) (Line: 19)
";}}}_sf2_meta|a:3:{s:1:"u";i:1732483431;s:1:"c";i:1732483431;s:1:"l";s:7:"2000000";}') (Line: 89)
Drupal\Core\Session\WriteSafeSessionHandler->write('93wVS4aLQD9mKwelI-o-GmXNbB0Qs3zFuoBDQJUEHOk', '_symfony_flashes|a:1:{s:5:"error";a:1:{i:0;O:25:"Drupal\Core\Render\Markup":1:{s:9:"*string";s:2733:"<em class="placeholder">Warning</em>: Error while sending QUERY packet. PID=14837 in <em class="placeholder">Drupal\Core\Database\Statement-&gt;execute()</em> (line <em class="placeholder">59</em> of <em class="placeholder">core/lib/Drupal/Core/Database/Statement.php</em>). Drupal\Core\Database\Statement-&gt;execute(Array, Array) (Line: 631)
Drupal\Core\Database\Connection-&gt;query(&#039;SELECT cid, data, created, expire, serialized, tags, checksum FROM {cache_discovery} WHERE cid IN ( :cids__0 ) ORDER BY cid&#039;, Array, Array) (Line: 358)
Drupal\Core\Database\Driver\mysql\Connection-&gt;query(&#039;SELECT cid, data, created, expire, serialized, tags, checksum FROM {cache_discovery} WHERE cid IN ( :cids[] ) ORDER BY cid&#039;, Array) (Line: 113)
Drupal\Core\Cache\DatabaseBackend-&gt;getMultiple(Array, ) (Line: 92)
Drupal\Core\Cache\DatabaseBackend-&gt;get(&#039;variant_plugins&#039;) (Line: 37)
Drupal\Core\Plugin\DefaultPluginManager-&gt;cacheGet(&#039;variant_plugins&#039;) (Line: 207)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getCachedDefinitions() (Line: 173)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getDefinitions() (Line: 22)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getDefinition(&#039;block_page&#039;) (Line: 16)
Drupal\Core\Plugin\Factory\ContainerFactory-&gt;createInstance(&#039;block_page&#039;, Array) (Line: 83)
Drupal\Component\Plugin\PluginManagerBase-&gt;createInstance(&#039;block_page&#039;) (Line: 236)
Drupal\Core\Render\MainContent\HtmlRenderer-&gt;prepare(Array, Object, Object) (Line: 117)
Drupal\Core\Render\MainContent\HtmlRenderer-&gt;renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber-&gt;onViewRenderArray(Object, &#039;kernel.view&#039;, Object)
call_user_func(Array, Object, &#039;kernel.view&#039;, Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher-&gt;dispatch(&#039;kernel.view&#039;, Object) (Line: 156)
Symfony\Component\HttpKernel\HttpKernel-&gt;handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel-&gt;handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session-&gt;handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle-&gt;handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache-&gt;pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache-&gt;handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware-&gt;handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware-&gt;handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel-&gt;handle(Object, 1, 1) (Line: 693)
Drupal\Core\DrupalKernel-&gt;handle(Object) (Line: 19)
";}}}_sf2_meta|a:3:{s:1:"u";i:1732483431;s:1:"c";i:1732483431;s:1:"l";s:7:"2000000";}') (Line: 67)
Symfony\Component\HttpFoundation\Session\Storage\Proxy\SessionHandlerProxy->write('93wVS4aLQD9mKwelI-o-GmXNbB0Qs3zFuoBDQJUEHOk', '_symfony_flashes|a:1:{s:5:"error";a:1:{i:0;O:25:"Drupal\Core\Render\Markup":1:{s:9:"*string";s:2733:"<em class="placeholder">Warning</em>: Error while sending QUERY packet. PID=14837 in <em class="placeholder">Drupal\Core\Database\Statement-&gt;execute()</em> (line <em class="placeholder">59</em> of <em class="placeholder">core/lib/Drupal/Core/Database/Statement.php</em>). Drupal\Core\Database\Statement-&gt;execute(Array, Array) (Line: 631)
Drupal\Core\Database\Connection-&gt;query(&#039;SELECT cid, data, created, expire, serialized, tags, checksum FROM {cache_discovery} WHERE cid IN ( :cids__0 ) ORDER BY cid&#039;, Array, Array) (Line: 358)
Drupal\Core\Database\Driver\mysql\Connection-&gt;query(&#039;SELECT cid, data, created, expire, serialized, tags, checksum FROM {cache_discovery} WHERE cid IN ( :cids[] ) ORDER BY cid&#039;, Array) (Line: 113)
Drupal\Core\Cache\DatabaseBackend-&gt;getMultiple(Array, ) (Line: 92)
Drupal\Core\Cache\DatabaseBackend-&gt;get(&#039;variant_plugins&#039;) (Line: 37)
Drupal\Core\Plugin\DefaultPluginManager-&gt;cacheGet(&#039;variant_plugins&#039;) (Line: 207)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getCachedDefinitions() (Line: 173)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getDefinitions() (Line: 22)
Drupal\Core\Plugin\DefaultPluginManager-&gt;getDefinition(&#039;block_page&#039;) (Line: 16)
Drupal\Core\Plugin\Factory\ContainerFactory-&gt;createInstance(&#039;block_page&#039;, Array) (Line: 83)
Drupal\Component\Plugin\PluginManagerBase-&gt;createInstance(&#039;block_page&#039;) (Line: 236)
Drupal\Core\Render\MainContent\HtmlRenderer-&gt;prepare(Array, Object, Object) (Line: 117)
Drupal\Core\Render\MainContent\HtmlRenderer-&gt;renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber-&gt;onViewRenderArray(Object, &#039;kernel.view&#039;, Object)
call_user_func(Array, Object, &#039;kernel.view&#039;, Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher-&gt;dispatch(&#039;kernel.view&#039;, Object) (Line: 156)
Symfony\Component\HttpKernel\HttpKernel-&gt;handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel-&gt;handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session-&gt;handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle-&gt;handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache-&gt;pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache-&gt;handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware-&gt;handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware-&gt;handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel-&gt;handle(Object, 1, 1) (Line: 693)
Drupal\Core\DrupalKernel-&gt;handle(Object) (Line: 19)
";}}}_sf2_meta|a:3:{s:1:"u";i:1732483431;s:1:"c";i:1732483431;s:1:"l";s:7:"2000000";}')
session_write_close() (Line: 244)
Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage->save() (Line: 198)
Drupal\Core\Session\SessionManager->save() (Line: 196)
Symfony\Component\HttpFoundation\Session\Session->save() (Line: 60)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 693)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

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Drupal\Core\Database\DatabaseExceptionWrapper: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: CREATE TABLE {cache_bootstrap} ( `cid` VARCHAR(255) CHARACTER SET ascii BINARY NOT NULL DEFAULT '' COMMENT 'Primary Key: Unique cache ID.', `data` LONGBLOB NULL DEFAULT NULL COMMENT 'A collection of data to cache.', `expire` INT NOT NULL DEFAULT 0 COMMENT 'A Unix timestamp indicating when the cache entry should expire, or -1 for never.', `created` DECIMAL(14, 3) NOT NULL DEFAULT 0 COMMENT 'A timestamp with millisecond precision indicating when the cache entry was created.', `serialized` SMALLINT NOT NULL DEFAULT 0 COMMENT 'A flag to indicate whether content is serialized (1) or not (0).', `tags` LONGTEXT NULL DEFAULT NULL COMMENT 'Space-separated list of cache tags for this entry.', `checksum` VARCHAR(255) CHARACTER SET ascii COLLATE ascii_general_ci NOT NULL COMMENT 'The tag invalidation checksum when this entry was saved.', PRIMARY KEY (`cid`), INDEX `expire` (`expire`), INDEX `created` (`created`) ) ENGINE = InnoDB DEFAULT CHARACTER SET utf8mb4 COMMENT 'Storage for the cache API.'; Array ( ) in Drupal\Core\Extension\ModuleHandler->writeCache() (line 337 of core/lib/Drupal/Core/Extension/ModuleHandler.php).

Drupal\Core\Extension\ModuleHandler->writeCache() (Line: 42)
Drupal\Core\EventSubscriber\RequestCloseSubscriber->onTerminate(Object, 'kernel.terminate', Object)
call_user_func(Array, Object, 'kernel.terminate', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.terminate', Object) (Line: 88)
Symfony\Component\HttpKernel\HttpKernel->terminate(Object, Object) (Line: 32)
Stack\StackedHttpKernel->terminate(Object, Object) (Line: 671)
Drupal\Core\DrupalKernel->terminate(Object, Object) (Line: 22)