diff --git a/www/commands/extendedgitgraph_refresh.php b/www/commands/extendedgitgraph_refresh.php
index a65c9fe..eff8dcd 100644
--- a/www/commands/extendedgitgraph_refresh.php
+++ b/www/commands/extendedgitgraph_refresh.php
@@ -7,6 +7,19 @@ require_once (__DIR__ . '/../internals/website.php');
 
 set_time_limit(900); // 15min
 
-$SITE->modules->ExtendedGitGraph()->update();
-$SITE->modules->ExtendedGitGraph()->updateCache();
+$r1 = $SITE->modules->ExtendedGitGraph()->update();
+if (!$r1)
+{
+	http_response_code(500);
+	echo 'EGG::update failed.';
+}
 
+$r2 = $SITE->modules->ExtendedGitGraph()->updateCache();
+if (!$r2)
+{
+	http_response_code(500);
+	echo 'EGG::updateCache failed.';
+}
+
+http_response_code(200);
+echo 'Done.';
\ No newline at end of file
diff --git a/www/extern/egg/EGGDatabase.php b/www/extern/egg/EGGDatabase.php
index a05d7fd..87574d7 100644
--- a/www/extern/egg/EGGDatabase.php
+++ b/www/extern/egg/EGGDatabase.php
@@ -45,6 +45,26 @@ class EGGDatabase
 		if(!$exists) $this->init();
 	}
 
+	public function openReadOnly()
+	{
+		$this->open();
+	}
+
+	public function beginTransaction()
+	{
+		$this->pdo->beginTransaction();
+	}
+
+	public function commitTransaction()
+	{
+		$this->pdo->commit();
+	}
+
+	public function abortTransactionIfExists()
+	{
+		if ($this->pdo !== null) $this->pdo->rollBack();
+	}
+
 	private function init()
 	{
 		$this->logger->proclog("Initialize new database '" . $this->path . "'");
@@ -133,7 +153,7 @@ class EGGDatabase
 					[":url", $url, PDO::PARAM_STR],
 				]);
 
-			if (count($repo) === 0) throw new Exception("No repo after insert [" . $source . "|" . $name . "]");
+			if (count($repo) === 0) throw new EGGException("No repo after insert [" . $source . "|" . $name . "]");
 
 			$this->logger->proclog("Inserted (new) repository [" . $source . "|" . $name . "] into database");
 		}
@@ -180,7 +200,7 @@ class EGGDatabase
 					[":nam", $name,     PDO::PARAM_STR],
 				]);
 
-			if (count($branch) === 0) throw new Exception("No branch after insert [" . $source . "|" . $repo->Name  . "|" . $name . "]");
+			if (count($branch) === 0) throw new EGGException("No branch after insert [" . $source . "|" . $repo->Name  . "|" . $name . "]");
 
 			$this->logger->proclog("Inserted (new) branch [" . $source . "|" . $repo->Name  . "|" . $name . "] into database");
 		}
diff --git a/www/extern/egg/EGGException.php b/www/extern/egg/EGGException.php
new file mode 100644
index 0000000..9052185
--- /dev/null
+++ b/www/extern/egg/EGGException.php
@@ -0,0 +1,14 @@
+<?php
+
+
+class EGGException extends Exception
+{
+	public $egg_message;
+
+	public function __construct($message)
+	{
+		parent::__construct($message);
+
+		$this->egg_message = $message;
+	}
+}
\ No newline at end of file
diff --git a/www/extern/egg/ExtendedGitGraph2.php b/www/extern/egg/ExtendedGitGraph2.php
index 62b796f..263995a 100644
--- a/www/extern/egg/ExtendedGitGraph2.php
+++ b/www/extern/egg/ExtendedGitGraph2.php
@@ -1,6 +1,7 @@
 <?php
 
 require_once 'Logger.php';
+require_once 'EGGException.php';
 require_once 'RemoteSource.php';
 require_once 'OutputGenerator.php';
 require_once 'EGGDatabase.php';
@@ -43,9 +44,9 @@ class ExtendedGitGraph2 implements ILogger
 			else if ($rmt['type'] === 'gitea')
 				$newsrc = new GiteaConnection($this, $rmt['name'], $rmt['url'], $rmt['filter'], $rmt['exclusions'], $rmt['username'], $rmt['password'] );
 			else
-				throw new Exception("Unknown remote-type: " . $rmt['type']);
+				throw new EGGException("Unknown remote-type: " . $rmt['type']);
 
-			if (array_key_exists($newsrc->getName(), $sourcenames)) throw new Exception("Duplicate source name: " . $newsrc->getName());
+			if (array_key_exists($newsrc->getName(), $sourcenames)) throw new EGGException("Duplicate source name: " . $newsrc->getName());
 
 			$this->sources []= $newsrc;
 			$sourcenames   []= $newsrc->getName();
@@ -61,6 +62,7 @@ class ExtendedGitGraph2 implements ILogger
 		try
 		{
 			$this->db->open();
+			$this->db->beginTransaction();
 
 			$this->proclog("Start incremental data update");
 			$this->proclog();
@@ -78,7 +80,21 @@ class ExtendedGitGraph2 implements ILogger
 
 			$this->proclog("Update finished.");
 
+			$this->db->commitTransaction();
+			$this->proclog("Data written.");
+
 			$this->db->close();
+
+			return true;
+		}
+		catch (EGGException $exception)
+		{
+			$this->proclog("ExtendedGitGraph2::update failed:");
+			$this->proclog($exception->egg_message);
+
+			$this->db->abortTransactionIfExists();
+
+			return false;
 		}
 		catch (Exception $exception)
 		{
@@ -87,14 +103,19 @@ class ExtendedGitGraph2 implements ILogger
 			$this->proclog($exception->getMessage());
 			$this->proclog();
 			$this->proclog($exception->getTraceAsString());
+
+			$this->db->abortTransactionIfExists();
+
+			return false;
 		}
 	}
 
-	public function updateCache(): string
+	public function updateCache(): ?string
 	{
 		try
 		{
-			$this->db->open();
+			$this->db->openReadOnly();
+			$this->db->beginTransaction();
 
 			$this->proclog("Start update cache");
 			$this->proclog();
@@ -106,6 +127,15 @@ class ExtendedGitGraph2 implements ILogger
 
 			return $data;
 		}
+		catch (EGGException $exception)
+		{
+			$this->proclog("ExtendedGitGraph2::updateCache failed:");
+			$this->proclog($exception->egg_message);
+
+			$this->db->abortTransactionIfExists();
+
+			return null;
+		}
 		catch (Exception $exception)
 		{
 			$this->proclog("(!) FATAL ERROR -- UNCAUGHT EXCEPTION THROWN");
@@ -113,6 +143,8 @@ class ExtendedGitGraph2 implements ILogger
 			$this->proclog($exception->getMessage());
 			$this->proclog();
 			$this->proclog($exception->getTraceAsString());
+
+			return null;
 		}
 	}
 
@@ -123,10 +155,12 @@ class ExtendedGitGraph2 implements ILogger
 	{
 		try
 		{
-			$this->db->open();
+			$this->db->openReadOnly();
 
 			$data = $this->outputter->loadFromCache();
 
+			$this->db->close();
+
 			return $data;
 		}
 		catch (Exception $exception)
diff --git a/www/extern/egg/RemoteSource.php b/www/extern/egg/RemoteSource.php
index f5b9868..ca519ff 100644
--- a/www/extern/egg/RemoteSource.php
+++ b/www/extern/egg/RemoteSource.php
@@ -379,13 +379,13 @@ class GithubConnection extends StandardGitConnection
 		$url = Utils::sharpFormat(self::URL_OAUTH_TOKEN, ['id'=>$this->oauth_id, 'secret'=>$this->oauth_secret, 'code'=>'egg']);
 		$fullresult = $result = file_get_contents($url);
 
+		if (Utils::startsWith($fullresult, 'error=')) throw new EGGException('GitHub Auth failed: ' . $fullresult);
+
 		$result = str_replace('access_token=', '', $result);
 		$result = str_replace('&scope=&token_type=bearer', '', $result);
 
 		$this->logger->proclog("Updated Github API token");
 
-		if (Utils::startsWith($result, "error=")) throw new Exception($fullresult);
-
 		if ($result!=='' && $result !== null && $this->apitokenpath !== null)
 			file_put_contents($this->apitokenpath, $result);
 
diff --git a/www/extern/egg/Utils.php b/www/extern/egg/Utils.php
index ae8002f..7820e4a 100644
--- a/www/extern/egg/Utils.php
+++ b/www/extern/egg/Utils.php
@@ -136,7 +136,7 @@ class Utils
 		{
 			$logger->proclog("Error recieving json: '" . $url . "'");
 			$logger->proclog(print_r(error_get_last(), true));
-			return [];
+			throw new EGGException("Error recieving json: '" . $url . "'");
 		}
 
 		return json_decode($response);
diff --git a/www/protected/vendor/.gitkeep b/www/protected/vendor/.gitkeep
new file mode 100644
index 0000000..e69de29