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# Warnings on admin page

Your Nextcloud server has a built-in configuration checker, and it reports its findings at the top of your Admin page. These are some of the warnings you might see, and what to do about them.

You can use the Nextcloud Security Scan to see if your system is up to date and well secured. We have ran this scan over public IP addresses in the past to try and reach out to extremely outdated systems and might again in the future. Please, protect your privacy and keep your server up to date! Privacy means little without security.

## Cache warnings

“No memory cache has been configured. To enhance your performance please configure a memcache if available.” Nextcloud supports multiple php caching extensions:

- APCu (minimum required PHP extension version 4.0.6)
- Memcached
- Redis (minimum required PHP extension version: 2.2.6)

You will see this warning if you have no caches installed and enabled, or if your cache does not have the required minimum version installed; older versions are disabled because of performance problems.

If you see “{Cache} below version {Version} is installed. for stability and performance reasons we recommend to update to a newer {Cache} version” then you need to upgrade, or, if you’re not using it, remove it.

You are not required to use any caches, but caches improve server performance. See Configuring memory caching.

## Transactional file locking is disabled

“Transactional file locking is disabled, this might lead to issues with race conditions.”

Please see Transactional file locking on how to correctly configure your environment for transactional file locking.

## You are accessing this site via HTTP

“You are accessing this site via HTTP. We strongly suggest you configure your server to require using HTTPS instead.” Please take this warning seriously; using HTTPS is a fundamental security measure. You must configure your Web server to support it, and then there are some settings in the Security section of your Nextcloud Admin page to enable. The following pages describe how to enable HTTPS on the Apache and Nginx Web servers.

Enabling SSL (on Apache)

Use HTTPS

Nginx configuration

## The test with getenv(“PATH”) only returns an empty response

Some environments are not passing a valid PATH variable to Nextcloud. The php-fpm configuration notes provides the information about how to configure your environment.

## The “Strict-Transport-Security” HTTP header is not configured

“The “Strict-Transport-Security” HTTP header is not configured to least “15552000” seconds. For enhanced security we recommend enabling HSTS as described in our security tips.”

The HSTS header needs to be configured within your Web server by following the Enable HTTP Strict Transport Security documentation

## /dev/urandom is not readable by PHP

“/dev/urandom is not readable by PHP which is highly discouraged for security reasons. Further information can be found in our documentation.”

This message is another one which needs to be taken seriously. Please have a look at the Give PHP read access to /dev/urandom documentation.

## Your Web server is not yet set up properly to allow file synchronization

“Your web server is not yet set up properly to allow file synchronization because the WebDAV interface seems to be broken.”

At the ownCloud community forums a larger FAQ is maintained containing various information and debugging hints.

## Outdated NSS / OpenSSL version

“cURL is using an outdated OpenSSL version (OpenSSL/$version). Please update your operating system or features such as installing and updating apps via the app store or Federated Cloud Sharing will not work reliably.”

“cURL is using an outdated NSS version (NSS/$version). Please update your operating system or features such as installing and updating apps via the app store or Federated Cloud Sharing will not work reliably.”

There are known bugs in older OpenSSL and NSS versions leading to misbehavior in combination with remote hosts using SNI. A technology used by most of the HTTPS websites. To ensure that Nextcloud will work properly you need to update OpenSSL to at least 1.0.2b or 1.0.1d. For NSS the patch version depends on your distribution and an heuristic is running the test which actually reproduces the bug. There are distributions such as RHEL/CentOS which have this backport still pending.

## Your Web server is not set up properly to resolve /.well-known/caldav/ or /.well-known/carddav/

Both URLs need to be correctly redirected to the DAV endpoint of Nextcloud. Please refer to Service discovery for more info.

## Some files have not passed the integrity check

Please refer to the Fixing invalid code integrity messages documentation how to debug this issue.

## Your database does not run with “READ COMMITED” transaction isolation level

“Your database does not run with “READ COMMITED” transaction isolation level. This can cause problems when multiple actions are executed in parallel.”

Please refer to Database “READ COMMITTED” transaction isolation level how to configure your database for this requirement.

- « Server configuration
- Using the occ command »