diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 412e2cd84..801791a4c 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -59,8 +59,7 @@ class UsersController < ApplicationController
       @user.touch(:profile_updated_at)
       redirect_to "/settings/#{@tab}"
     else
-      Honeycomb.add_field("error",
-                          @user.errors.messages.reject { |_, v| v.empty? })
+      Honeycomb.add_field("error", @user.errors.messages.reject { |_, v| v.empty? })
       Honeycomb.add_field("errored", true)
       render :edit, status: :bad_request
     end
diff --git a/app/lib/url.rb b/app/lib/url.rb
index e106c702f..bd7d4d011 100644
--- a/app/lib/url.rb
+++ b/app/lib/url.rb
@@ -60,6 +60,8 @@ module URL
   # @param user [User] the user to create the URL for
   def self.user(user)
     url(user.username)
+  rescue URI::InvalidURIError # invalid username containing spaces will result in an error
+    nil
   end
 
   def self.organization(organization)
diff --git a/app/views/users/_profile.html.erb b/app/views/users/_profile.html.erb
index ec66b896b..56d588471 100644
--- a/app/views/users/_profile.html.erb
+++ b/app/views/users/_profile.html.erb
@@ -4,7 +4,7 @@
 
 <div class="crayons-card mb-6 p-6 grid gap-6">
   <div class="flex items-center">
-    <a href="<%= app_url(current_user.username) %>" aria-label="Go to your profile page" class="mr-2">
+    <a href="<%= user_url(current_user) || '#' %>" aria-label="Go to your profile page" class="mr-2">
       <img src="https://d2fltix0v2e0sb.cloudfront.net/dev-badge.svg" alt="<%= community_name %> badge" height="32" width="32" class="dev-badge crayons-icon" />
     </a>
     <p>Add the <%= community_name %> badge to your personal site. <a href="/p/badges">Click here for the code</a>.</p>
diff --git a/app/views/users/edit.html.erb b/app/views/users/edit.html.erb
index f17b6b64f..0e6e93c26 100644
--- a/app/views/users/edit.html.erb
+++ b/app/views/users/edit.html.erb
@@ -49,7 +49,7 @@
         </h1>
       <% else %>
         <h1 class="fs-xl s:fs-3xl">
-          Settings for <a href="<%= user_url(@user) %>">@<%= @user.username.truncate(User::USERNAME_MAX_LENGTH) %></a>
+          Settings for <a href="<%= user_url(@user) || '#' %>">@<%= @user.username.truncate(User::USERNAME_MAX_LENGTH) %></a>
         </h1>
       <% end %>
     </header>
diff --git a/spec/system/user/user_edits_profile_spec.rb b/spec/system/user/user_edits_profile_spec.rb
new file mode 100644
index 000000000..b3fb0a9f0
--- /dev/null
+++ b/spec/system/user/user_edits_profile_spec.rb
@@ -0,0 +1,20 @@
+require "rails_helper"
+
+RSpec.describe "User edits their profile", type: :system do
+  let(:user) { create(:user, saw_onboarding: true) }
+
+  before do
+    sign_in user
+  end
+
+  describe "visiting /settings/profile" do
+    it "renders an error if the username contains spaces and thus is invalid" do
+      visit "/settings/profile"
+
+      fill_in "user[username]", with: "a b c"
+      click_button "Save"
+
+      expect(page).to have_text("Username is invalid")
+    end
+  end
+end