diff --git a/CHANGELOG.md b/CHANGELOG.md
index 47211a0a6..13cb7866e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,18 +5,26 @@
   * The update command is now much more deterministic as it does not take the already installed packages into account
   * Package installation now performs all network operations first before doing any changes on disk, to reduce the chances of ending up with a partially updated vendor dir
   * Partial updates and require/remove are now much faster as they only load the metadata required for the updated packages
-  * Added support for parallel downloads of package metadata and zip files, this requires that the curl extension is present
+  * Added a platform-check step when vendor/autoload.php gets initialized which checks the current PHP version/extensions match what is expected and fails hard otherwise. Can be disabled with the platform-check config option
+  * Added a [`Composer\InstalledVersions`](https://github.com/composer/composer/blob/d89342dc434d52c88e0e06ce3982da739a467f13/src/Composer/InstalledVersions.php) class which is autoloaded in every project and lets you check which packages/versions are present at runtime
+  * Added a `composer-runtime-api` virtual package which you can require (as e.g. `^2.0`) to ensure things like the InstalledVersions class above are present. It will effectively force people to use Composer 2.x to install your project
+  * Added support for parallel downloads of package metadata and zip files, this requires that the curl extension is present and we thus strongly recommend enabling curl
   * Added much clearer dependency resolution error reporting for common error cases
   * Added support for TTY mode on Linux/OSX/WSL so that script handlers now run in interactive mode
   * Added `only`, `exclude` and `canonical` options to all repositories, see [repository priorities](https://getcomposer.org/repoprio) for details
   * Added support for lib-zip platform package
   * Added `pre-operations-exec` event to be fired before the packages get installed/upgraded/removed
   * Added `pre-pool-create` event to be fired before the package pool for the dependency solver is created, which lets you modify the list of packages going in
+  * Added `post-file-download` event to be fired after package dist files are downloaded, which lets you do additional checks on the files
+  * Added --unused flag to `remove` command to make sure any packages which are not needed anymore get removed
   * Added --dry-run flag to `require` and `remove` commands
+  * Added --no-install flag to `update`, `require` and `remove` commands to disable the install step and only do the update step (composer.lock file update)
   * Added --with-dependencies and --with-all-dependencies flag aliases to `require` and `remove` commands for consistency with `update`
   * Added more info to `vendor/composer/installed.json`, a dev key stores whether dev requirements were installed, and every package now has an install-path key with its install location
   * Added COMPOSER_DISABLE_NETWORK which if set makes Composer do its best to run offline. This can be useful when you have poor connectivity or to do benchmarking without network jitter
+  * Added --json and --merge flags to `config` command to allow editing complex `extra.*` values by using json as input
   * Added confirmation prompt when running Composer as superuser in interactive mode
+  * Added --no-check-version to `validate` command to remove the warning in case the version is defined
   * Fixed suggest output being very spammy, it now is only one line long and shows more rarely
   * Fixed conflict rules like e.g. >=5 from matching dev-master, as it is not normalized to 9999999-dev internally anymore
 
diff --git a/UPGRADE-2.0.md b/UPGRADE-2.0.md
index ae2e9b55f..c8bcedf70 100644
--- a/UPGRADE-2.0.md
+++ b/UPGRADE-2.0.md
@@ -2,11 +2,13 @@
 
 ## For composer CLI users
 
+- The new platform-check feature means that Composer checks the runtime PHP version and available extensions to ensure they match the project dependencies. If a mismatch is found, it exits with error details to make sure problems are not overlooked. To avoid issues when deploying to production it is recommended to run `composer check-platform-reqs` with the production PHP process as part of your build or deployment process.
 - If a packages exists in a higher priority repository, it will now be entirely ignored in lower priority repositories. See [repository priorities](https://getcomposer.org/repoprio) for details.
 - Invalid PSR-0 / PSR-4 class configurations will not autoload anymore in optimized-autoloader mode, as per the warnings introduced in 1.10
 - Package names now must comply to our [naming guidelines](doc/04-schema.md#name) or Composer will abort, as per the warnings introduced in 1.8.1
 - Deprecated --no-suggest flag as it is not needed anymore
-- `update` now lists changes to the lock file first, and then the changes applied when installing the lock file to the vendor dir
+- PEAR support (repository, downloader, etc.) has been removed
+- `update` now lists changes to the lock file first (update step), and then the changes applied when installing the lock file to the vendor dir (install step)
 - `HTTPS_PROXY_REQUEST_FULLURI` if not specified will now default to false as this seems to work better in most environments
 
 ## For integrators and plugin authors