diff --git a/backend/src/middleware/permissionsMiddleware.js b/backend/src/middleware/permissionsMiddleware.js
index 906285d12..9aef8646b 100644
--- a/backend/src/middleware/permissionsMiddleware.js
+++ b/backend/src/middleware/permissionsMiddleware.js
@@ -122,37 +122,41 @@ const isAllowedToChangeGroupMemberRole = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
   if (!(user && user.id)) return false
-  const adminId = user.id
+  const currentUserId = user.id
   const { groupId, userId, roleInGroup } = args
-  if (adminId === userId) return false
+  if (currentUserId === userId) return false
   const session = driver.session()
   const readTxPromise = session.readTransaction(async (transaction) => {
     const transactionResponse = await transaction.run(
       `
-        MATCH (admin:User {id: $adminId})-[adminMembership:MEMBER_OF]->(group:Group {id: $groupId})
+        MATCH (currentUser:User {id: $currentUserId})-[currentUserMembership:MEMBER_OF]->(group:Group {id: $groupId})
         OPTIONAL MATCH (group)<-[userMembership:MEMBER_OF]-(member:User {id: $userId})
-        RETURN group {.*}, admin {.*, myRoleInGroup: adminMembership.role}, member {.*, myRoleInGroup: userMembership.role}
+        RETURN group {.*}, currentUser {.*, myRoleInGroup: currentUserMembership.role}, member {.*, myRoleInGroup: userMembership.role}
       `,
-      { groupId, adminId, userId },
+      { groupId, currentUserId, userId },
     )
     return {
-      admin: transactionResponse.records.map((record) => record.get('admin'))[0],
+      currentUser: transactionResponse.records.map((record) => record.get('currentUser'))[0],
       group: transactionResponse.records.map((record) => record.get('group'))[0],
       member: transactionResponse.records.map((record) => record.get('member'))[0],
     }
   })
   try {
-    const { admin, group, member } = await readTxPromise
+    const { currentUser, group, member } = await readTxPromise
+    const groupExists = !!group
+    const currentUserExists = !!currentUser
+    const userIsMember = !!member
+    const sameUserRoleInGroup = member && member.myRoleInGroup === roleInGroup
+    const userIsOwner = member && ['owner'].includes(member.myRoleInGroup)
+    const currentUserIsAdmin = currentUser && ['admin'].includes(currentUser.myRoleInGroup)
+    const adminCanSetRole = ['pending', 'usual', 'admin'].includes(roleInGroup)
+    const currentUserIsOwner = currentUser && ['owner'].includes(currentUser.myRoleInGroup)
+    const ownerCanSetRole = ['pending', 'usual', 'admin', 'owner'].includes(roleInGroup)
     return (
-      !!group &&
-      !!admin &&
-      (!member ||
-        (!!member &&
-          (member.myRoleInGroup === roleInGroup || !['owner'].includes(member.myRoleInGroup)))) &&
-      ((['admin'].includes(admin.myRoleInGroup) &&
-        ['pending', 'usual', 'admin'].includes(roleInGroup)) ||
-        (['owner'].includes(admin.myRoleInGroup) &&
-          ['pending', 'usual', 'admin', 'owner'].includes(roleInGroup)))
+      groupExists &&
+      currentUserExists &&
+      (!userIsMember || (userIsMember && (sameUserRoleInGroup || !userIsOwner))) &&
+      ((currentUserIsAdmin && adminCanSetRole) || (currentUserIsOwner && ownerCanSetRole))
     )
   } catch (error) {
     throw new Error(error)
diff --git a/webapp/components/Group/GroupMember.vue b/webapp/components/Group/GroupMember.vue
index db5635c1f..830318767 100644
--- a/webapp/components/Group/GroupMember.vue
+++ b/webapp/components/Group/GroupMember.vue
@@ -179,12 +179,17 @@ export default {
     },
     async addMemberToGroup() {
       const newRole = 'usual'
+      if (this.groupMembers.find((member) => member.id === this.slugUser[0].id)) {
+        this.$toast.error(
+          this.$t('group.errors.userAlreadyMember', { slug: this.slugUser[0].slug }),
+        )
+        return
+      }
       try {
         await this.$apollo.mutate({
           mutation: changeGroupMemberRoleMutation(),
           variables: { groupId: this.groupId, userId: this.slugUser[0].id, roleInGroup: newRole },
         })
-        // this.$apollo.queries.GroupMembers.refetch()
         this.$emit('loadGroupMembers')
         this.slugUser = []
         this.form.query = ''
diff --git a/webapp/locales/de.json b/webapp/locales/de.json
index 39fd2de9f..31a514470 100644
--- a/webapp/locales/de.json
+++ b/webapp/locales/de.json
@@ -422,6 +422,9 @@
       "groupName": "Einstellungen für „{name}“",
       "title": "Meine Gruppe ändern"
     },
+    "errors": {
+      "userAlreadyMember": "Nutzer @{slug} ist bereits Mitglied"
+    },
     "follow": "Folge",
     "foundation": "Gründung",
     "general": "Allgemein",
diff --git a/webapp/locales/en.json b/webapp/locales/en.json
index 18b579df4..4b63033c1 100644
--- a/webapp/locales/en.json
+++ b/webapp/locales/en.json
@@ -422,6 +422,9 @@
       "groupName": "Settings Of “{name}”",
       "title": "Edit My Group"
     },
+    "errors": {
+      "userAlreadyMember": "User @{slug} is already a member"
+    },
     "follow": "Follow",
     "foundation": "Foundation",
     "general": "General",