diff --git a/lib/web/auth/oauth2/index.js b/lib/web/auth/oauth2/index.js
index b96fd1aea..b0ffa5e8a 100644
--- a/lib/web/auth/oauth2/index.js
+++ b/lib/web/auth/oauth2/index.js
@@ -62,6 +62,11 @@ function parseProfile (data) {
   const displayName = extractProfileAttribute(data, config.oauth2.userProfileDisplayNameAttr)
   const email = extractProfileAttribute(data, config.oauth2.userProfileEmailAttr)
 
+  if (id === undefined && username === undefined) {
+    logger.error('oauth2 auth failed: id and username are undefined')
+    throw new Error('User ID or Username required')
+  }
+
   return {
     id: id || username,
     username,
diff --git a/public/docs/release-notes.md b/public/docs/release-notes.md
index f3378ec61..0173ead0c 100644
--- a/public/docs/release-notes.md
+++ b/public/docs/release-notes.md
@@ -9,6 +9,7 @@ If you use SAML authentication, please make sure to update your SAML configurati
 See: https://docs.hedgedoc.org/configuration/#saml-login `CMD_SAML_ATTRIBUTE_USERNAME` or `CMD_SAML_ATTRIBUTE_EMAIL`  
 
 ### Bugfixes
+- Check if a valid user id is present when using OAuth2
 - Abort SAML login if NameID is undefined instead of logging in with a user named "undefined"
 - Set default values for username and email attribute mapping in SAML configuration