2 exception(s):
Exception #0 (Zend_Db_Adapter_Exception): SQLSTATE[08004] [1040] Too many connections
Exception #1 (PDOException): SQLSTATE[08004] [1040] Too many connections

Exception #0 (Zend_Db_Adapter_Exception): SQLSTATE[08004] [1040] Too many connections
<pre>#1 Zend_Db_Adapter_Pdo_Mysql->_connect() called at [vendor/magento/framework/DB/Adapter/Pdo/Mysql.php:428]
#2 Magento\Framework\DB\Adapter\Pdo\Mysql->_connect() called at [vendor/magento/zendframework1/library/Zend/Db/Adapter/Abstract.php:861]
#3 Zend_Db_Adapter_Abstract->quote() called at [vendor/magento/zendframework1/library/Zend/Db/Adapter/Abstract.php:932]
#4 Zend_Db_Adapter_Abstract->quoteInto() called at [vendor/magento/framework/DB/Adapter/Pdo/Mysql.php:1533]
#5 Magento\Framework\DB\Adapter\Pdo\Mysql->quoteInto() called at [vendor/magento/zendframework1/library/Zend/Db/Select.php:1031]
#6 Zend_Db_Select->_where() called at [vendor/magento/zendframework1/library/Zend/Db/Select.php:496]
#7 Zend_Db_Select->where() called at [vendor/magento/framework/DB/Select.php:127]
#8 Magento\Framework\DB\Select->where() called at [vendor/magento/framework/Model/ResourceModel/Db/AbstractDb.php:361]
#9 Magento\Framework\Model\ResourceModel\Db\AbstractDb->_getLoadSelect() called at [vendor/magento/framework/Model/ResourceModel/Db/AbstractDb.php:332]
#10 Magento\Framework\Model\ResourceModel\Db\AbstractDb->load() called at [vendor/magento/framework/Model/AbstractModel.php:543]
#11 Magento\Framework\Model\AbstractModel->load() called at [vendor/magento/framework/Flag.php:147]
#12 Magento\Framework\Flag->loadSelf() called at [vendor/magento/module-staging/Model/Update/VersionHistory.php:78]
#13 Magento\Staging\Model\Update\VersionHistory->getFlag() called at [vendor/magento/module-staging/Model/Update/VersionHistory.php:58]
#14 Magento\Staging\Model\Update\VersionHistory->getCurrentId() called at [vendor/magento/module-staging/Model/VersionManager.php:192]
#15 Magento\Staging\Model\VersionManager->getCurrentVersionId() called at [vendor/magento/module-staging/Model/VersionManager.php:121]
#16 Magento\Staging\Model\VersionManager->getVersion() called at [vendor/magento/module-staging/Model/VersionManager.php:181]
#17 Magento\Staging\Model\VersionManager->isPreviewVersion() called at [generated/code/Magento/Staging/Model/VersionManager/Proxy.php:127]
#18 Magento\Staging\Model\VersionManager\Proxy->isPreviewVersion() called at [vendor/magento/module-staging/Plugin/Store/Model/StoreResolver.php:59]
#19 Magento\Staging\Plugin\Store\Model\StoreResolver->aroundGetCurrentStoreId() called at [vendor/magento/framework/Interception/Interceptor.php:135]
#20 Magento\Store\Model\StoreResolver\Interceptor->Magento\Framework\Interception\{closure}() called at [vendor/magento/framework/Interception/Interceptor.php:153]
#21 Magento\Store\Model\StoreResolver\Interceptor->___callPlugins() called at [generated/code/Magento/Store/Model/StoreResolver/Interceptor.php:23]
#22 Magento\Store\Model\StoreResolver\Interceptor->getCurrentStoreId() called at [vendor/magento/module-store/Model/StoreManager.php:160]
#23 Magento\Store\Model\StoreManager->getStore() called at [generated/code/Magento/Store/Model/StoreManagerInterface/Proxy.php:119]
#24 Magento\Store\Model\StoreManagerInterface\Proxy->getStore() called at [vendor/magento/module-store/Model/Resolver/Store.php:30]
#25 Magento\Store\Model\Resolver\Store->getScope() called at [vendor/magento/framework/App/Config/ScopeCodeResolver.php:49]
#26 Magento\Framework\App\Config\ScopeCodeResolver->resolve() called at [vendor/magento/framework/App/Config.php:69]
#27 Magento\Framework\App\Config->getValue() called at [vendor/magento/module-backend/App/Area/FrontNameResolver.php:123]
#28 Magento\Backend\App\Area\FrontNameResolver->isHostBackend() called at [vendor/magento/module-backend/App/Area/FrontNameResolver.php:106]
#29 Magento\Backend\App\Area\FrontNameResolver->getFrontName() called at [vendor/magento/framework/App/AreaList.php:73]
#30 Magento\Framework\App\AreaList->getCodeByFrontName() called at [vendor/magento/framework/App/Http.php:111]
#31 Magento\Framework\App\Http->launch() called at [vendor/magento/framework/App/Bootstrap.php:264]
#32 Magento\Framework\App\Bootstrap->run() called at [pub/index.php:30]
</pre>

Exception #1 (PDOException): SQLSTATE[08004] [1040] Too many connections
<pre>#1 Zend_Db_Adapter_Pdo_Abstract->_connect() called at [vendor/magento/zendframework1/library/Zend/Db/Adapter/Pdo/Mysql.php:111]
#2 Zend_Db_Adapter_Pdo_Mysql->_connect() called at [vendor/magento/framework/DB/Adapter/Pdo/Mysql.php:428]
#3 Magento\Framework\DB\Adapter\Pdo\Mysql->_connect() called at [vendor/magento/zendframework1/library/Zend/Db/Adapter/Abstract.php:861]
#4 Zend_Db_Adapter_Abstract->quote() called at [vendor/magento/zendframework1/library/Zend/Db/Adapter/Abstract.php:932]
#5 Zend_Db_Adapter_Abstract->quoteInto() called at [vendor/magento/framework/DB/Adapter/Pdo/Mysql.php:1533]
#6 Magento\Framework\DB\Adapter\Pdo\Mysql->quoteInto() called at [vendor/magento/zendframework1/library/Zend/Db/Select.php:1031]
#7 Zend_Db_Select->_where() called at [vendor/magento/zendframework1/library/Zend/Db/Select.php:496]
#8 Zend_Db_Select->where() called at [vendor/magento/framework/DB/Select.php:127]
#9 Magento\Framework\DB\Select->where() called at [vendor/magento/framework/Model/ResourceModel/Db/AbstractDb.php:361]
#10 Magento\Framework\Model\ResourceModel\Db\AbstractDb->_getLoadSelect() called at [vendor/magento/framework/Model/ResourceModel/Db/AbstractDb.php:332]
#11 Magento\Framework\Model\ResourceModel\Db\AbstractDb->load() called at [vendor/magento/framework/Model/AbstractModel.php:543]
#12 Magento\Framework\Model\AbstractModel->load() called at [vendor/magento/framework/Flag.php:147]
#13 Magento\Framework\Flag->loadSelf() called at [vendor/magento/module-staging/Model/Update/VersionHistory.php:78]
#14 Magento\Staging\Model\Update\VersionHistory->getFlag() called at [vendor/magento/module-staging/Model/Update/VersionHistory.php:58]
#15 Magento\Staging\Model\Update\VersionHistory->getCurrentId() called at [vendor/magento/module-staging/Model/VersionManager.php:192]
#16 Magento\Staging\Model\VersionManager->getCurrentVersionId() called at [vendor/magento/module-staging/Model/VersionManager.php:121]
#17 Magento\Staging\Model\VersionManager->getVersion() called at [vendor/magento/module-staging/Model/VersionManager.php:181]
#18 Magento\Staging\Model\VersionManager->isPreviewVersion() called at [generated/code/Magento/Staging/Model/VersionManager/Proxy.php:127]
#19 Magento\Staging\Model\VersionManager\Proxy->isPreviewVersion() called at [vendor/magento/module-staging/Plugin/Store/Model/StoreResolver.php:59]
#20 Magento\Staging\Plugin\Store\Model\StoreResolver->aroundGetCurrentStoreId() called at [vendor/magento/framework/Interception/Interceptor.php:135]
#21 Magento\Store\Model\StoreResolver\Interceptor->Magento\Framework\Interception\{closure}() called at [vendor/magento/framework/Interception/Interceptor.php:153]
#22 Magento\Store\Model\StoreResolver\Interceptor->___callPlugins() called at [generated/code/Magento/Store/Model/StoreResolver/Interceptor.php:23]
#23 Magento\Store\Model\StoreResolver\Interceptor->getCurrentStoreId() called at [vendor/magento/module-store/Model/StoreManager.php:160]
#24 Magento\Store\Model\StoreManager->getStore() called at [generated/code/Magento/Store/Model/StoreManagerInterface/Proxy.php:119]
#25 Magento\Store\Model\StoreManagerInterface\Proxy->getStore() called at [vendor/magento/module-store/Model/Resolver/Store.php:30]
#26 Magento\Store\Model\Resolver\Store->getScope() called at [vendor/magento/framework/App/Config/ScopeCodeResolver.php:49]
#27 Magento\Framework\App\Config\ScopeCodeResolver->resolve() called at [vendor/magento/framework/App/Config.php:69]
#28 Magento\Framework\App\Config->getValue() called at [vendor/magento/module-backend/App/Area/FrontNameResolver.php:123]
#29 Magento\Backend\App\Area\FrontNameResolver->isHostBackend() called at [vendor/magento/module-backend/App/Area/FrontNameResolver.php:106]
#30 Magento\Backend\App\Area\FrontNameResolver->getFrontName() called at [vendor/magento/framework/App/AreaList.php:73]
#31 Magento\Framework\App\AreaList->getCodeByFrontName() called at [vendor/magento/framework/App/Http.php:111]
#32 Magento\Framework\App\Http->launch() called at [vendor/magento/framework/App/Bootstrap.php:264]
#33 Magento\Framework\App\Bootstrap->run() called at [pub/index.php:30]
</pre>