diff --git a/src/main/scala/app/SystemSettingsController.scala b/src/main/scala/app/SystemSettingsController.scala
index 82aabbd..2292853 100644
--- a/src/main/scala/app/SystemSettingsController.scala
+++ b/src/main/scala/app/SystemSettingsController.scala
@@ -11,6 +11,7 @@
 import java.io.FileInputStream
 import plugin.{Plugin, PluginSystem}
 import org.scalatra.Ok
+import util.Implicits._
 
 class SystemSettingsController extends SystemSettingsControllerBase
   with AccountService with AdminAuthenticator
diff --git a/src/main/scala/plugin/PluginSystem.scala b/src/main/scala/plugin/PluginSystem.scala
index 2afaa6e..0524d2f 100644
--- a/src/main/scala/plugin/PluginSystem.scala
+++ b/src/main/scala/plugin/PluginSystem.scala
@@ -10,6 +10,8 @@
 import service.RepositoryService.RepositoryInfo
 import Security._
 import service.PluginService
+import model.Profile._
+import profile.simple._
 
 /**
  * Provides extension points to plug-ins.
@@ -22,14 +24,15 @@
   private val pluginsMap = scala.collection.mutable.Map[String, Plugin]()
   private val repositoriesList = scala.collection.mutable.ListBuffer[PluginRepository]()
 
-  def install(plugin: Plugin): Unit = {
+  def install(plugin: Plugin)(implicit session: Session): Unit = {
     pluginsMap.put(plugin.id, plugin)
   }
 
   def plugins: List[Plugin] = pluginsMap.values.toList
 
-  def uninstall(id: String): Unit = {
+  def uninstall(id: String)(implicit session: Session): Unit = {
     pluginsMap.remove(id)
+    deletePlugin(id)
   }
 
   def repositories: List[PluginRepository] = repositoriesList.toList
@@ -37,7 +40,7 @@
   /**
    * Initializes the plugin system. Load scripts from GITBUCKET_HOME/plugins.
    */
-  def init(): Unit = {
+  def init()(implicit session: Session): Unit = {
     if(initialized.compareAndSet(false, true)){
       // Load installed plugins
       val pluginDir = new java.io.File(PluginHome)
@@ -52,7 +55,7 @@
   }
 
   // TODO Method name seems to not so good.
-  def installPlugin(id: String): Unit = {
+  def installPlugin(id: String)(implicit session: Session): Unit = {
     val pluginDir = new java.io.File(PluginHome)
 
     val scalaFile = new java.io.File(pluginDir, id + "/plugin.scala")
diff --git a/src/main/scala/service/PluginService.scala b/src/main/scala/service/PluginService.scala
index 12f97fb..74523b2 100644
--- a/src/main/scala/service/PluginService.scala
+++ b/src/main/scala/service/PluginService.scala
@@ -14,6 +14,6 @@
 
   def deletePlugin(pluginId: String)(implicit s: Session): Unit = Plugins.filter(_.pluginId === pluginId.bind).delete
 
-  def getPlugin(pluginId: String): Option[Plugin] = Plugins.filter(_.pluginId === pluginId.bind).firstOption
+  def getPlugin(pluginId: String)(implicit s: Session): Option[Plugin] = Plugins.filter(_.pluginId === pluginId.bind).firstOption
 
 }
diff --git a/src/main/scala/servlet/AutoUpdateListener.scala b/src/main/scala/servlet/AutoUpdateListener.scala
index eb52c5b..4619c24 100644
--- a/src/main/scala/servlet/AutoUpdateListener.scala
+++ b/src/main/scala/servlet/AutoUpdateListener.scala
@@ -180,10 +180,12 @@
       System.setProperty("gitbucket.home", datadir)
     }
     org.h2.Driver.load()
-    event.getServletContext.setInitParameter("db.url", s"jdbc:h2:${DatabaseHome};MVCC=true")
 
-    logger.debug("Start schema update")
+    val context = event.getServletContext
+    context.setInitParameter("db.url", s"jdbc:h2:${DatabaseHome};MVCC=true")
+
     defining(getConnection(event.getServletContext)){ conn =>
+      logger.debug("Start schema update")
       try {
         defining(getCurrentVersion()){ currentVersion =>
           if(currentVersion == headVersion){
@@ -193,7 +195,6 @@
           } else {
             versions.takeWhile(_ != currentVersion).reverse.foreach(_.update(conn))
             FileUtils.writeStringToFile(versionFile, headVersion.versionString, "UTF-8")
-            conn.commit()
             logger.debug(s"Updated from ${currentVersion.versionString} to ${headVersion.versionString}")
           }
         }
@@ -204,17 +205,27 @@
           conn.rollback()
         }
       }
+      logger.debug("End schema update")
     }
-    logger.debug("End schema update")
 
-    logger.debug("Starting plugin system...")
-    plugin.PluginSystem.init()
+    getDatabase(context).withSession { implicit session =>
+      logger.debug("Starting plugin system...")
+      try {
+        plugin.PluginSystem.init()
 
-    scheduler.start()
-    PluginUpdateJob.schedule(scheduler)
-    logger.debug("PluginUpdateJob is started.")
+        scheduler.start()
+        PluginUpdateJob.schedule(scheduler)
+        logger.debug("PluginUpdateJob is started.")
 
-    logger.debug("Plugin system is initialized.")
+        logger.debug("Plugin system is initialized.")
+      } catch {
+        case ex: Throwable => {
+          logger.error("Failed to initialize plugin system", ex)
+          ex.printStackTrace()
+          session.rollback()
+        }
+      }
+    }
   }
 
   def contextDestroyed(sce: ServletContextEvent): Unit = {
@@ -227,4 +238,10 @@
       servletContext.getInitParameter("db.user"),
       servletContext.getInitParameter("db.password"))
 
+  private def getDatabase(servletContext: ServletContext): scala.slick.jdbc.JdbcBackend.Database =
+    slick.jdbc.JdbcBackend.Database.forURL(
+      servletContext.getInitParameter("db.url"),
+      servletContext.getInitParameter("db.user"),
+      servletContext.getInitParameter("db.password"))
+
 }