diff --git a/thehive-backend/app/services/OAuth2Srv.scala b/thehive-backend/app/services/OAuth2Srv.scala
index af8ad47163..d52078d5b8 100644
--- a/thehive-backend/app/services/OAuth2Srv.scala
+++ b/thehive-backend/app/services/OAuth2Srv.scala
@@ -79,7 +79,7 @@ class OAuth2Srv(
     }
 
   private def getAuthTokenAndAuthenticate(clientId: String, code: String)(implicit request: RequestHeader): Future[AuthContext] = {
-    logger.debug("Getting user token with the code from the response!")
+    logger.debug("Getting user token with the code from the response")
     withOAuth2Config { cfg ⇒
       ws.url(cfg.tokenUrl)
         .post(
@@ -99,6 +99,7 @@ class OAuth2Srv(
         .flatMap { r ⇒
           r.status match {
             case Status.OK ⇒
+              logger.debug("Getting user info using access token")
               val accessToken = (r.json \ "access_token").asOpt[String].getOrElse("")
               val authHeader  = "Authorization" → s"bearer $accessToken"
               ws.url(cfg.userUrl)
@@ -106,15 +107,15 @@ class OAuth2Srv(
                 .get()
                 .flatMap { userResponse ⇒
                   if (userResponse.status != Status.OK) {
-                    Future.failed(AuthenticationError(s"unexpected response from server: ${userResponse.status} ${userResponse.body}"))
+                    Future.failed(AuthenticationError(s"Unexpected response from server: ${userResponse.status} ${userResponse.body}"))
                   } else {
                     val response = userResponse.json.asInstanceOf[JsObject]
                     getOrCreateUser(response, authHeader)
                   }
                 }
             case _ ⇒
-              logger.error(s"unexpected response from server: ${r.status} ${r.body}")
-              Future.failed(AuthenticationError("unexpected response from server"))
+              logger.error(s"Unexpected response from server: ${r.status} ${r.body}")
+              Future.failed(AuthenticationError("Unexpected response from server"))
           }
         }
     }
diff --git a/thehive-backend/app/services/mappers/GroupUserMapper.scala b/thehive-backend/app/services/mappers/GroupUserMapper.scala
index d0b50c4bfd..cf036ce379 100644
--- a/thehive-backend/app/services/mappers/GroupUserMapper.scala
+++ b/thehive-backend/app/services/mappers/GroupUserMapper.scala
@@ -55,14 +55,6 @@ class GroupUserMapper(
         case None       ⇒ Seq.empty[String]
       }
     }
-
-    def apply(input: String): Seq[String] = parseAll(expr, input) match {
-      case Success(result, _)  ⇒ result
-      case failure : NoSuccess ⇒ {
-        logger.error(s"Can't parse groups list: ${failure.msg}")
-        Seq.empty[String]
-      }
-    }
   }
 
   override def getUserFields(jsValue: JsValue, authHeader: Option[(String, String)]): Future[Fields] = {
@@ -70,30 +62,36 @@ class GroupUserMapper(
       case Some(groupsEndpointUrl) ⇒ {
         logger.debug(s"Retreiving groups from ${groupsEndpointUrl}")
         val apiCall = authHeader.fold(ws.url(groupsEndpointUrl))(headers ⇒ ws.url(groupsEndpointUrl).addHttpHeaders(headers))
-        apiCall.get.flatMap { r ⇒
-          val jsonGroups = (r.json \ groupsAttrName).as[Seq[String]]
-          mapGroupsAndBuildUserFields(jsValue, jsonGroups)
-        }
+        apiCall.get.flatMap { r ⇒ extractGroupsThenBuildUserFields(jsValue, r.json) }
       }
       case None ⇒ {
-        val jsonGroups: Seq[String] = (jsValue \ groupsAttrName) match {
-          // Groups received as valid JSON array
-          case JsDefined(JsArray(groupsList)) ⇒ groupsList.map(_.as[String]).toList
-          // Groups list received as string (invalid JSON, for example: "ROLE" or "['Role 1', ROLE2, 'Role_3']")
-          case JsDefined(JsString(groupsStr)) ⇒ (new RoleListParser).apply(groupsStr)
-          // Invalid group list
-          case JsDefined(error) ⇒ {
-            logger.error(s"Invalid groups list received in user info: '${error}' of type ${error.getClass}")
-            Seq.empty[String]
-          }
-          // Groups field is undefined
-          case _: JsUndefined ⇒ {
-            logger.error(s"OAuth2 not configured properly: groups attribute ${groupsAttrName} doesn't exist in user info")
-            Seq.empty[String]
-          }
+        logger.debug(s"Extracting groups from user info")
+        extractGroupsThenBuildUserFields(jsValue, jsValue)
+      }
+    }
+  }
+
+  private def extractGroupsThenBuildUserFields(jsValue: JsValue, groupsContainer: JsValue): Future[Fields] = {
+    (groupsContainer \ groupsAttrName) match {
+      // Groups received as valid JSON array
+      case JsDefined(JsArray(groupsList)) ⇒ mapGroupsAndBuildUserFields(jsValue, groupsList.map(_.as[String]).toList)
+
+      // Groups list received as string (invalid JSON, for example: "ROLE" or "['Role 1', ROLE2, 'Role_3']")
+      case JsDefined(JsString(groupsStr)) ⇒ {
+        val parser = new RoleListParser
+        parser.parseAll(parser.expr, groupsStr) match {
+          case parser.Success(result, _) ⇒ mapGroupsAndBuildUserFields(jsValue, result)
+          case err: parser.NoSuccess     ⇒ Future.failed(AuthenticationError(s"User info fails: can't parse groups list (${err.msg})"))
         }
-        mapGroupsAndBuildUserFields(jsValue, jsonGroups)
       }
+
+      // Invalid group list
+      case JsDefined(error) ⇒
+        Future.failed(AuthenticationError(s"User info fails: invalid groups list received in user info ('${error}' of type ${error.getClass})"))
+
+      // Groups field is undefined
+      case _: JsUndefined ⇒
+        Future.failed(AuthenticationError(s"User info fails: groups attribute ${groupsAttrName} doesn't exist in user info"))
     }
   }
 
@@ -102,10 +100,10 @@ class GroupUserMapper(
     val roles       = if (mappedRoles.nonEmpty) mappedRoles else defaultRoles
 
     if (roles.isEmpty) {
-      Future.failed(AuthorizationError(s"No matched roles for user."))
+      Future.failed(AuthorizationError(s"No matched roles for user"))
 
     } else {
-      logger.debug(s"Computed roles: ${roles}")
+      logger.debug(s"Computed roles: ${roles.mkString(", ")}")
 
       val fields = for {
         login ← (jsValue \ loginAttrName).validate[String]
@@ -113,7 +111,7 @@ class GroupUserMapper(
       } yield Fields(Json.obj("login" → login, "name" → name, "roles" → roles))
       fields match {
         case JsSuccess(f, _) ⇒ Future.successful(f)
-        case JsError(errors) ⇒ Future.failed(AuthenticationError(s"User info fails: ${errors.map(_._1).mkString}"))
+        case JsError(errors) ⇒ Future.failed(AuthenticationError(s"User info fails: ${errors.map(_._2).map(_.map(_.messages.mkString(", ")).mkString("; ")).mkString}"))
       }
     }
   }
diff --git a/thehive-backend/app/services/mappers/SimpleUserMapper.scala b/thehive-backend/app/services/mappers/SimpleUserMapper.scala
index 323d6f9715..598d9d2ece 100644
--- a/thehive-backend/app/services/mappers/SimpleUserMapper.scala
+++ b/thehive-backend/app/services/mappers/SimpleUserMapper.scala
@@ -37,7 +37,7 @@ class SimpleUserMapper(
     } yield Fields(Json.obj("login" → login, "name" → name, "roles" → roles))
     fields match {
       case JsSuccess(f, _) ⇒ Future.successful(f)
-      case JsError(errors) ⇒ Future.failed(AuthenticationError(s"User info fails: ${errors.map(_._1).mkString}"))
+      case JsError(errors) ⇒ Future.failed(AuthenticationError(s"User info fails: ${errors.map(_._2).map(_.map(_.messages.mkString(", ")).mkString("; ")).mkString}"))
     }
   }
 }