diff --git a/app/models/concerns/avatarable.rb b/app/models/concerns/avatarable.rb
index d35e37935fb0bb7f4634ad5d390625ded08a1c9f..318df11727e2d93d90332b53763f8e78a884b44e 100644
--- a/app/models/concerns/avatarable.rb
+++ b/app/models/concerns/avatarable.rb
@@ -21,7 +21,7 @@ module Avatarable
 
   def avatar_type
     unless self.avatar.image?
-      self.errors.add :avatar, "only images allowed"
+      errors.add :avatar, "file format is not supported. Please try one of the following supported formats: #{AvatarUploader::IMAGE_EXT.join(', ')}"
     end
   end
 
diff --git a/app/models/group.rb b/app/models/group.rb
index 8d183006c658bb1c6a2320ca1974cec9ef09f1e6..8e391412b521248e9855baf8ff845971053bae89 100644
--- a/app/models/group.rb
+++ b/app/models/group.rb
@@ -189,12 +189,6 @@ class Group < Namespace
     owners.include?(user) && owners.size == 1
   end
 
-  def avatar_type
-    unless self.avatar.image?
-      self.errors.add :avatar, "only images allowed"
-    end
-  end
-
   def post_create_hook
     Gitlab::AppLogger.info("Group \"#{name}\" was created")
 
diff --git a/changelogs/unreleased/43771-improve-avatar-error-message.yml b/changelogs/unreleased/43771-improve-avatar-error-message.yml
new file mode 100644
index 0000000000000000000000000000000000000000..1fae10f4d1f28565a6bd056e5a4fdf2593affc4a
--- /dev/null
+++ b/changelogs/unreleased/43771-improve-avatar-error-message.yml
@@ -0,0 +1,5 @@
+---
+title: Change avatar error message to include allowed file formats
+merge_request: 17747
+author: Fabian Schneider
+type: changed
diff --git a/spec/models/group_spec.rb b/spec/models/group_spec.rb
index abfc0896a4119366a8519fc4b6928fa0a1dc5664..d620943693c879da0759dc048c2fbbd5e480b635 100644
--- a/spec/models/group_spec.rb
+++ b/spec/models/group_spec.rb
@@ -240,7 +240,7 @@ describe Group do
 
     it "is false if avatar is html page" do
       group.update_attribute(:avatar, 'uploads/avatar.html')
-      expect(group.avatar_type).to eq(["only images allowed"])
+      expect(group.avatar_type).to eq(["file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff"])
     end
   end
 
diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index e970cd7dfdb33b02d8a47215a583623d4b79d420..943b27f285dd2af319335e6d1d52a682d6e64053 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -922,7 +922,7 @@ describe Project do
 
     it 'is false if avatar is html page' do
       project.update_attribute(:avatar, 'uploads/avatar.html')
-      expect(project.avatar_type).to eq(['only images allowed'])
+      expect(project.avatar_type).to eq(['file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff'])
     end
   end
 
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 5680eb249852554f57a5035d6cd68d310d6b8288..c61674fff13836b98ad09ad0d23e984b71a79a87 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -1222,7 +1222,7 @@ describe User do
     it 'is false if avatar is html page' do
       user.update_attribute(:avatar, 'uploads/avatar.html')
 
-      expect(user.avatar_type).to eq(['only images allowed'])
+      expect(user.avatar_type).to eq(['file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff'])
     end
   end