diff --git a/phpBB/adm/style/acp_ext_catalog.html b/phpBB/adm/style/acp_ext_catalog.html
index 23b966c615..fff5c551a6 100644
--- a/phpBB/adm/style/acp_ext_catalog.html
+++ b/phpBB/adm/style/acp_ext_catalog.html
@@ -62,6 +62,21 @@
 				<label><input type="radio" name="enable_packagist" class="radio" value="0"{% if not settings.enable_packagist %} checked="checked" {% endif %} /> {{ lang('NO') }}</label>
 			</dd>
 		</dl>
+		<dl>
+			<dt>
+				<label for="minimum_stability">{{ lang('COMPOSER_MINIMUM_STABILITY') }}{{ lang('COLON') }}</label><br />
+				<span class="explain">
+					<strong class="error">{{ lang('WARNING') }}{{ lang('COLON') }}</strong> {{ lang('COMPOSER_MINIMUM_STABILITY_EXPLAIN') }}
+				</span>
+			</dt>
+			<dd>
+				<select id="minimum_stability" name="minimum_stability">
+					{% for stability in settings.stabilities %}
+						<option value="{{ stability }}"{% if stability === settings.minimum_stability %} selected='selected'{% endif %}>{{ lang('STABILITY_' ~ stability|upper) }}</option>
+					{% endfor %}
+				</select>
+			</dd>
+		</dl>
 
 		<p class="submit-buttons">
 			<input class="button1" type="submit" name="update" value="{{ lang('SUBMIT') }}" />&nbsp;
diff --git a/phpBB/includes/acp/acp_extensions.php b/phpBB/includes/acp/acp_extensions.php
index 2e93f2a09d..79c51bfd70 100644
--- a/phpBB/includes/acp/acp_extensions.php
+++ b/phpBB/includes/acp/acp_extensions.php
@@ -587,6 +587,8 @@ class acp_extensions
 				if (!$this->config['exts_composer_packagist'] && $this->request->is_set('enable_packagist') && confirm_box(true))
 				{
 					$this->config->set('exts_composer_packagist', true);
+					$composer_manager->reset_cache();
+
 					trigger_error($language->lang('CONFIG_UPDATED') . adm_back_link($this->u_action));
 				}
 
@@ -601,12 +603,25 @@ class acp_extensions
 					$enable_packagist = $this->request->variable('enable_packagist', false);
 					$enable_on_install = $this->request->variable('enable_on_install', false);
 					$purge_on_remove = $this->request->variable('purge_on_remove', false);
+					$minimum_stability = $this->request->variable('minimum_stability', 'stable');
 					$repositories = array_unique(explode("\n", $this->request->variable('repositories', '')));
 
+					$previous_minimum_stability = $this->config['exts_composer_minimum_stability'];
+					$previous_repositories = $this->config['exts_composer_repositories'];
+					$previous_enable_packagist = $this->config['exts_composer_packagist'];
+
 					$this->config->set('exts_composer_enable_on_install', $enable_on_install);
 					$this->config->set('exts_composer_purge_on_remove', $purge_on_remove);
+					$this->config->set('exts_composer_minimum_stability', $minimum_stability);
 					$this->config->set('exts_composer_repositories', json_encode($repositories, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES));
 
+					if ($minimum_stability != $previous_minimum_stability
+						|| $repositories != $previous_repositories
+						|| $enable_packagist != $previous_enable_packagist)
+					{
+						$composer_manager->reset_cache();
+					}
+
 					if (!$this->config['exts_composer_packagist'] && $enable_packagist)
 					{
 						$s_hidden_fields = build_hidden_fields(array(
@@ -651,6 +666,8 @@ class acp_extensions
 					'enable_packagist' => $this->config['exts_composer_packagist'],
 					'enable_on_install' => $this->config['exts_composer_enable_on_install'],
 					'purge_on_remove' => $this->config['exts_composer_purge_on_remove'],
+					'minimum_stability' => $this->config['exts_composer_minimum_stability'],
+					'stabilities' => array_keys(\Composer\Package\BasePackage::$stabilities),
 					'repositories' => json_decode($this->config['exts_composer_repositories'], true),
 				]);
 				$this->template->assign_var('enabled', $manager->check_requirements());
diff --git a/phpBB/language/en/acp/extensions.php b/phpBB/language/en/acp/extensions.php
index 0a3a43c3a7..53ba5bf859 100644
--- a/phpBB/language/en/acp/extensions.php
+++ b/phpBB/language/en/acp/extensions.php
@@ -165,4 +165,14 @@ $lang = array_merge($lang, array(
 	'EXTENSIONS_UPDATED'			=> 'Extensions successfully updated.',
 
 	'EXTENSIONS_COMPOSER_NOT_WRITABLE'	=> 'TODO: some required files / directory are not writable => disable ',
+
+	'STABILITY_STABLE'	=> 'stable',
+	'STABILITY_RC'		=> 'RC',
+	'STABILITY_BETA'	=> 'beta',
+	'STABILITY_ALPHA'	=> 'alpha',
+	'STABILITY_DEV'		=> 'dev',
+
+	'COMPOSER_MINIMUM_STABILITY'			=> 'Minimum stability',
+	'COMPOSER_MINIMUM_STABILITY_EXPLAIN'	=> 'TODO: why it is dangerous to change that',
+
 ));
diff --git a/phpBB/phpbb/composer/installer.php b/phpBB/phpbb/composer/installer.php
index 74ea531673..2b805288da 100644
--- a/phpBB/phpbb/composer/installer.php
+++ b/phpBB/phpbb/composer/installer.php
@@ -55,6 +55,11 @@ class installer
 	 */
 	protected $packages_vendor_dir = 'vendor-ext/';
 
+	/**
+	 * @var string Minimum stability
+	 */
+	protected $minimum_stability = 'stable';
+
 	/**
 	 * @var string phpBB root path
 	 */
@@ -88,6 +93,7 @@ class installer
 			$this->packagist           = (bool) $config['exts_composer_packagist'];
 			$this->composer_filename   = $config['exts_composer_json_file'];
 			$this->packages_vendor_dir = $config['exts_composer_vendor_dir'];
+			$this->minimum_stability   = $config['exts_composer_minimum_stability'];
 		}
 
 		$this->root_path = $root_path;
@@ -484,6 +490,7 @@ class installer
 				'cache-dir' => 'store/composer',
 				'vendor-dir'=> $this->packages_vendor_dir,
 			],
+			'minimum-stability' => $this->minimum_stability,
 		];
 
 		$this->ext_json_file_backup = null;
diff --git a/phpBB/phpbb/composer/manager.php b/phpBB/phpbb/composer/manager.php
index cffc6c8566..fbd14c5783 100644
--- a/phpBB/phpbb/composer/manager.php
+++ b/phpBB/phpbb/composer/manager.php
@@ -263,6 +263,18 @@ class manager implements manager_interface
 		return $this->available_packages;
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
+	public function reset_cache()
+	{
+		$this->cache->destroy('_composer_' . $this->package_type . '_available');
+
+		$this->available_packages = null;
+		$this->managed_packages = null;
+		$this->all_managed_packages = null;
+	}
+
 	/**
 	 * {@inheritdoc}
 	 */
diff --git a/phpBB/phpbb/composer/manager_interface.php b/phpBB/phpbb/composer/manager_interface.php
index ab36f58dc9..9fae7a0e9c 100644
--- a/phpBB/phpbb/composer/manager_interface.php
+++ b/phpBB/phpbb/composer/manager_interface.php
@@ -78,6 +78,11 @@ interface manager_interface
 	 */
 	public function get_available_packages();
 
+	/**
+	 * Reset the cache
+	 */
+	public function reset_cache();
+
 	/**
 	 * Start managing a manually installed package
 	 *