diff --git a/inc/inc.ClassExtensionMgr.php b/inc/inc.ClassExtensionMgr.php
index be648449f..385b744bc 100644
--- a/inc/inc.ClassExtensionMgr.php
+++ b/inc/inc.ClassExtensionMgr.php
@@ -85,6 +85,12 @@ class ExtensionMgr {
 	 */
 	protected $errmsgs;
 
+	/**
+	 * @var string[] $warnmsg list of warning message from last operation
+	 * @access protected
+	 */
+	protected $warnmsgs;
+
 	/*
 	 * Name of json file containg available extension from repository
 	 */
@@ -431,6 +437,7 @@ $EXT_CONF = '.var_export($EXT_CONF, true).';');
 		}
 
 		$this->errmsgs = array();
+		$this->warnmsgs = array();
 
 		if(!isset($extconf['constraints']['depends']['seeddms'])) {
 			$this->errmsgs[] = "Missing dependency on SeedDMS";
@@ -447,6 +454,9 @@ $EXT_CONF = '.var_export($EXT_CONF, true).';');
 		if(!isset($extconf['author'])) {
 			$this->errmsgs[] = "Missing author";
 		}
+		if(!isset($extconf['changes'])) {
+			$this->warnmsgs[] = "Missing changes";
+		}
 
 		if(!isset($options['noconstraints']) || $options['noconstraints'] == false) {
 			if(isset($extconf['constraints']['depends'])) {
@@ -749,4 +759,13 @@ $EXT_CONF = '.var_export($EXT_CONF, true).';');
 	public function getErrorMsgs() { /* {{{ */
 		return $this->errmsgs;
 	} /* }}} */
+
+	/**
+	 * Return all warning messages
+	 *
+	 * @return string[]
+	 */
+	public function getWarningMsgs() { /* {{{ */
+		return $this->warnmsgs;
+	} /* }}} */
 }