How do i fix this?

1 exception(s): Exception #0 (Exception): Warning: file_put_contents(/var/www/html/var/cache//mage-tags/mage—40d_CONFIG_SCOPES): failed to open stream: Permission denied in /var/www/html/vendor/colinmollenhour/cache-backend-file/File.php on line 691 Exception #0 (Exception): Warning: file_put_contents(/var/www/html/var/cache//mage-tags/mage—40d_CONFIG_SCOPES): failed to open stream: Permission denied in /var/www/html/vendor/colinmollenhour/cache-backend-file/File.php on line 691 <pre>#1 file_put_contents() called at [vendor/colinmollenhour/cache-backend-file/File.php:691] #2 Cm_Cache_Backend_File->_updateIdsTags() called at [vendor/colinmollenhour/cache-backend-file/File.php:203] #3 Cm_Cache_Backend_File->save() called at [vendor/magento/zendframework1/library/Zend/Cache/Core.php:390] #4 Zend_Cache_Core->save() called at [vendor/magento/framework/Cache/Core.php:74] #5 MagentoFrameworkCacheCore->save() called at [vendor/magento/framework/Cache/Frontend/Adapter/Zend.php:63] #6 MagentoFrameworkCacheFrontendAdapterZend->save() called at [vendor/magento/framework/Cache/Frontend/Decorator/Bare.php:75] #7 MagentoFrameworkCacheFrontendDecoratorBare->save() called at [vendor/magento/framework/Cache/Frontend/Decorator/TagScope.php:52] #8 MagentoFrameworkCacheFrontendDecoratorTagScope->save() called at [vendor/magento/framework/Cache/Frontend/Decorator/Bare.php:75] #9 MagentoFrameworkCacheFrontendDecoratorBare->save() called at [vendor/magento/framework/Cache/Frontend/Decorator/Bare.php:75] #10 MagentoFrameworkCacheFrontendDecoratorBare->save() called at [vendor/magento/framework/App/Cache/Type/AccessProxy.php:85] #11 MagentoFrameworkAppCacheTypeAccessProxy->save() called at [vendor/magento/framework/Cache/Frontend/Decorator/Bare.php:75] #12 MagentoFrameworkCacheFrontendDecoratorBare->save() called at [vendor/magento/framework/Cache/Frontend/Decorator/TagScope.php:52] #13 MagentoFrameworkCacheFrontendDecoratorTagScope->save() called at [vendor/magento/module-config/App/Config/Type/System.php:317] #14 MagentoConfigAppConfigTypeSystem->cacheData() called at [vendor/magento/framework/Cache/LockGuardedCacheLoader.php:80] #15 MagentoFrameworkCacheLockGuardedCacheLoader->lockedLoadData() called at [vendor/magento/module-config/App/Config/Type/System.php:261] #16 MagentoConfigAppConfigTypeSystem->loadDefaultScopeData() called at [vendor/magento/module-config/App/Config/Type/System.php:195] #17 MagentoConfigAppConfigTypeSystem->getWithParts() called at [vendor/magento/module-config/App/Config/Type/System.php:169] #18 MagentoConfigAppConfigTypeSystem->get() called at [vendor/magento/framework/App/Config.php:132] #19 MagentoFrameworkAppConfig->get() called at [vendor/magento/module-backend/App/Config.php:51] #20 MagentoBackendAppConfig->getValue() called at [vendor/magento/module-backend/App/Area/FrontNameResolver.php:109] #21 MagentoBackendAppAreaFrontNameResolver->getFrontName() called at [vendor/magento/module-backend/Helper/Data.php:209] #22 MagentoBackendHelperData->getAreaFrontName() called at [vendor/magento/module-backend/App/Request/PathInfoProcessor.php:50] #23 MagentoBackendAppRequestPathInfoProcessor->process() called at [generated/code/Magento/Backend/App/Request/PathInfoProcessor/Proxy.php:95] #24 MagentoBackendAppRequestPathInfoProcessorProxy->process() called at [vendor/magento/framework/App/Request/Http.php:147] #25 MagentoFrameworkAppRequestHttp->getOriginalPathInfo() called at [vendor/magento/framework/App/Request/Http.php:162] #26 MagentoFrameworkAppRequestHttp->getPathInfo() called at [vendor/magento/framework/App/Request/Http.php:217] #27 MagentoFrameworkAppRequestHttp->getFrontName() called at [vendor/magento/framework/App/Http.php:111] #28 MagentoFrameworkAppHttp->launch() called at [vendor/magento/framework/App/Bootstrap.php:261] #29 MagentoFrameworkAppBootstrap->run() called at [pub/index.php:40] </pre>

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