diff --git a/changelogs/unreleased/sh-fix-oauth2-callback-caps.yml b/changelogs/unreleased/sh-fix-oauth2-callback-caps.yml
new file mode 100644
index 0000000000000000000000000000000000000000..8d17900cb79934cc2a42dee234dfe797ffcafbb4
--- /dev/null
+++ b/changelogs/unreleased/sh-fix-oauth2-callback-caps.yml
@@ -0,0 +1,5 @@
+---
+title: Downcase aliased OAuth2 callback providers
+merge_request: 24877
+author:
+type: fixed
diff --git a/config/routes/import.rb b/config/routes/import.rb
index 69df82611f29c1ea7873cae7804106eeea84c952..da5c31d0062492381a0e88ddda3b3ed5da2af178 100644
--- a/config/routes/import.rb
+++ b/config/routes/import.rb
@@ -1,7 +1,7 @@
 # Alias import callbacks under the /users/auth endpoint so that
 # the OAuth2 callback URL can be restricted under http://example.com/users/auth
 # instead of http://example.com.
-Devise.omniauth_providers.each do |provider|
+Devise.omniauth_providers.map(&:downcase).each do |provider|
   next if provider == 'ldapmain'
 
   get "/users/auth/-/import/#{provider}/callback", to: "import/#{provider}#callback", as: "users_import_#{provider}_callback"