diff --git a/.ruby-version b/.ruby-version
index 30f69e8c..fd2a0186 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.5.9
+3.1.0
diff --git a/Gemfile b/Gemfile
index 9c966d32..991df83d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,7 +5,7 @@ end
 
 source 'https://rubygems.org'
 
-ruby ENV['OSEM_RUBY_VERSION'] || '2.5.9'
+ruby ENV['OSEM_RUBY_VERSION'] || '3.1.0'
 
 # rails-assets requires >= 1.8.4
 if Gem::Version.new(Bundler::VERSION) < Gem::Version.new('1.8.4')
@@ -14,7 +14,7 @@ end
 
 # as web framework
 if next?
-  gem 'rails', '~> 6'
+  gem 'rails', '~> 7'
 else
   gem 'rails', '~> 5.2'
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index 680e8037..2e84b18d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,6 +1,29 @@
+GEM
+  remote: https://rails-assets.org/
+  specs:
+    rails-assets-bootstrap (3.3.6)
+      rails-assets-jquery (>= 1.9.1, < 3)
+    rails-assets-bootstrap-markdown (2.10.0)
+      rails-assets-bootstrap (~> 3)
+    rails-assets-bootstrap-select (1.13.3)
+      rails-assets-bootstrap (>= 3.0.0)
+      rails-assets-jquery (>= 1.9.1, < 4)
+    rails-assets-date.format (1.2.3)
+    rails-assets-holderjs (2.9.6)
+    rails-assets-jquery (2.2.4)
+    rails-assets-jquery-smooth-scroll (2.2.0)
+      rails-assets-jquery (>= 1.7.0)
+    rails-assets-markdown (0.5.0)
+    rails-assets-momentjs (2.22.2)
+    rails-assets-spectrum (1.8.0)
+      rails-assets-jquery (>= 1.7.2)
+    rails-assets-tinycolor (1.4.1)
+    rails-assets-to-markdown (3.1.1)
+    rails-assets-trianglify (1.2.0)
+    rails-assets-waypoints (4.0.1)
+
 GEM
   remote: https://rubygems.org/
-  remote: https://rails-assets.org/
   specs:
     Ascii85 (1.1.0)
     actioncable (5.2.6)
@@ -197,7 +220,7 @@ GEM
     ffi (1.15.4)
     font-awesome-rails (4.7.0.7)
       railties (>= 3.2, < 7)
-    formatador (0.3.0)
+    formatador (1.1.0)
     formtastic (3.1.5)
       actionpack (>= 3.2.13)
     formtastic-bootstrap (3.1.1)
@@ -285,7 +308,7 @@ GEM
       actionmailer (>= 3.2)
       letter_opener (~> 1.0)
       railties (>= 3.2)
-    listen (3.7.0)
+    listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     loofah (2.12.0)
@@ -423,26 +446,6 @@ GEM
       bundler (>= 1.3.0)
       railties (= 5.2.6)
       sprockets-rails (>= 2.0.0)
-    rails-assets-bootstrap (3.3.6)
-      rails-assets-jquery (>= 1.9.1, < 3)
-    rails-assets-bootstrap-markdown (2.10.0)
-      rails-assets-bootstrap (~> 3)
-    rails-assets-bootstrap-select (1.13.3)
-      rails-assets-bootstrap (>= 3.0.0)
-      rails-assets-jquery (>= 1.9.1, < 4)
-    rails-assets-date.format (1.2.3)
-    rails-assets-holderjs (2.9.6)
-    rails-assets-jquery (2.2.4)
-    rails-assets-jquery-smooth-scroll (2.2.0)
-      rails-assets-jquery (>= 1.7.0)
-    rails-assets-markdown (0.5.0)
-    rails-assets-momentjs (2.22.2)
-    rails-assets-spectrum (1.8.0)
-      rails-assets-jquery (>= 1.7.2)
-    rails-assets-tinycolor (1.4.1)
-    rails-assets-to-markdown (3.1.1)
-    rails-assets-trianglify (1.2.0)
-    rails-assets-waypoints (4.0.1)
     rails-controller-testing (1.0.5)
       actionpack (>= 5.0.1.rc1)
       actionview (>= 5.0.1.rc1)
@@ -581,7 +584,7 @@ GEM
       activesupport (>= 4.2.0)
     sort_alphabetical (1.1.0)
       unicode_utils (>= 1.2.2)
-    spring (2.1.1)
+    spring (4.0.0)
     spring-commands-rspec (1.0.4)
       spring (>= 0.9.1)
     sprockets (3.7.2)
@@ -762,7 +765,7 @@ DEPENDENCIES
   whenever
 
 RUBY VERSION
-   ruby 2.5.9p229
+   ruby 3.1.0
 
 BUNDLED WITH
-   1.17.3
+   2.3.3
diff --git a/Gemfile.next.lock b/Gemfile.next.lock
index fe03953a..61837968 100644
--- a/Gemfile.next.lock
+++ b/Gemfile.next.lock
@@ -1,76 +1,105 @@
 GEM
-  remote: https://rubygems.org/
   remote: https://rails-assets.org/
+  specs:
+    rails-assets-bootstrap (3.4.1)
+      rails-assets-jquery (>= 1.9.1, < 4)
+    rails-assets-bootstrap-markdown (2.10.0)
+      rails-assets-bootstrap (~> 3)
+    rails-assets-bootstrap-select (1.13.10)
+      rails-assets-bootstrap (>= 3.0.0)
+      rails-assets-jquery (>= 1.9.1, < 4)
+    rails-assets-date.format (1.2.3)
+    rails-assets-holderjs (2.9.6)
+    rails-assets-jquery (3.4.1)
+    rails-assets-jquery-smooth-scroll (2.2.0)
+      rails-assets-jquery (>= 1.7.0)
+    rails-assets-markdown (0.5.0)
+    rails-assets-momentjs (2.22.2)
+    rails-assets-spectrum (1.8.0)
+      rails-assets-jquery (>= 1.7.2)
+    rails-assets-tinycolor (1.4.1)
+    rails-assets-to-markdown (3.1.1)
+    rails-assets-trianglify (1.2.0)
+    rails-assets-waypoints (4.0.1)
+
+GEM
+  remote: https://rubygems.org/
   specs:
     Ascii85 (1.1.0)
-    actioncable (6.1.4)
-      actionpack (= 6.1.4)
-      activesupport (= 6.1.4)
+    actioncable (7.0.1)
+      actionpack (= 7.0.1)
+      activesupport (= 7.0.1)
       nio4r (~> 2.0)
       websocket-driver (>= 0.6.1)
-    actionmailbox (6.1.4)
-      actionpack (= 6.1.4)
-      activejob (= 6.1.4)
-      activerecord (= 6.1.4)
-      activestorage (= 6.1.4)
-      activesupport (= 6.1.4)
+    actionmailbox (7.0.1)
+      actionpack (= 7.0.1)
+      activejob (= 7.0.1)
+      activerecord (= 7.0.1)
+      activestorage (= 7.0.1)
+      activesupport (= 7.0.1)
       mail (>= 2.7.1)
-    actionmailer (6.1.4)
-      actionpack (= 6.1.4)
-      actionview (= 6.1.4)
-      activejob (= 6.1.4)
-      activesupport (= 6.1.4)
+      net-imap
+      net-pop
+      net-smtp
+    actionmailer (7.0.1)
+      actionpack (= 7.0.1)
+      actionview (= 7.0.1)
+      activejob (= 7.0.1)
+      activesupport (= 7.0.1)
       mail (~> 2.5, >= 2.5.4)
+      net-imap
+      net-pop
+      net-smtp
       rails-dom-testing (~> 2.0)
-    actionpack (6.1.4)
-      actionview (= 6.1.4)
-      activesupport (= 6.1.4)
-      rack (~> 2.0, >= 2.0.9)
+    actionpack (7.0.1)
+      actionview (= 7.0.1)
+      activesupport (= 7.0.1)
+      rack (~> 2.0, >= 2.2.0)
       rack-test (>= 0.6.3)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.2.0)
-    actiontext (6.1.4)
-      actionpack (= 6.1.4)
-      activerecord (= 6.1.4)
-      activestorage (= 6.1.4)
-      activesupport (= 6.1.4)
+    actiontext (7.0.1)
+      actionpack (= 7.0.1)
+      activerecord (= 7.0.1)
+      activestorage (= 7.0.1)
+      activesupport (= 7.0.1)
+      globalid (>= 0.6.0)
       nokogiri (>= 1.8.5)
-    actionview (6.1.4)
-      activesupport (= 6.1.4)
+    actionview (7.0.1)
+      activesupport (= 7.0.1)
       builder (~> 3.1)
       erubi (~> 1.4)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.1, >= 1.2.0)
-    active_model_serializers (0.10.12)
-      actionpack (>= 4.1, < 6.2)
-      activemodel (>= 4.1, < 6.2)
+    active_model_serializers (0.10.13)
+      actionpack (>= 4.1, < 7.1)
+      activemodel (>= 4.1, < 7.1)
       case_transform (>= 0.2)
       jsonapi-renderer (>= 0.1.1.beta1, < 0.3)
-    activejob (6.1.4)
-      activesupport (= 6.1.4)
+    activejob (7.0.1)
+      activesupport (= 7.0.1)
       globalid (>= 0.3.6)
-    activemodel (6.1.4)
-      activesupport (= 6.1.4)
-    activerecord (6.1.4)
-      activemodel (= 6.1.4)
-      activesupport (= 6.1.4)
-    activestorage (6.1.4)
-      actionpack (= 6.1.4)
-      activejob (= 6.1.4)
-      activerecord (= 6.1.4)
-      activesupport (= 6.1.4)
-      marcel (~> 1.0.0)
+    activemodel (7.0.1)
+      activesupport (= 7.0.1)
+    activerecord (7.0.1)
+      activemodel (= 7.0.1)
+      activesupport (= 7.0.1)
+    activestorage (7.0.1)
+      actionpack (= 7.0.1)
+      activejob (= 7.0.1)
+      activerecord (= 7.0.1)
+      activesupport (= 7.0.1)
+      marcel (~> 1.0)
       mini_mime (>= 1.1.0)
-    activesupport (6.1.4)
+    activesupport (7.0.1)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 1.6, < 2)
       minitest (>= 5.1)
       tzinfo (~> 2.0)
-      zeitwerk (~> 2.3)
-    acts_as_commentable_with_threading (2.0.1)
-      activerecord (>= 4.0)
-      activesupport (>= 4.0)
-      awesome_nested_set (>= 3.0)
+    acts_as_commentable_with_threading (1.2.0)
+      activerecord (>= 3.0)
+      activesupport (>= 3.0)
+      awesome_nested_set (>= 2.0)
     acts_as_list (1.0.4)
       activerecord (>= 4.2)
     addressable (2.8.0)
@@ -83,8 +112,8 @@ GEM
     ast (2.4.2)
     autoprefixer-rails (10.3.1.0)
       execjs (~> 2)
-    awesome_nested_set (3.4.0)
-      activerecord (>= 4.0.0, < 7.0)
+    awesome_nested_set (2.1.6)
+      activerecord (>= 3.0.0)
     aws_cf_signer (0.1.3)
     bcrypt (3.1.16)
     bindex (0.8.1)
@@ -159,10 +188,10 @@ GEM
       activerecord (>= 5.a)
       database_cleaner-core (~> 2.0.0)
     database_cleaner-core (2.0.1)
-    delayed_job (4.1.9)
-      activesupport (>= 3.0, < 6.2)
-    delayed_job_active_record (4.1.6)
-      activerecord (>= 3.0, < 6.2)
+    delayed_job (4.1.10)
+      activesupport (>= 3.0, < 8.0)
+    delayed_job_active_record (4.1.7)
+      activerecord (>= 3.0, < 8.0)
       delayed_job (>= 3.0, < 5)
     devise (4.8.0)
       bcrypt (~> 3.0)
@@ -173,6 +202,7 @@ GEM
     devise_ichain_authenticatable (0.3.2)
       devise (>= 2.2)
     diff-lcs (1.4.4)
+    digest (3.1.0)
     docile (1.4.0)
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
@@ -212,8 +242,8 @@ GEM
     fastimage (2.2.5)
     feature (1.4.0)
     ffi (1.15.3)
-    font-awesome-rails (4.7.0.7)
-      railties (>= 3.2, < 7)
+    font-awesome-rails (4.7.0.8)
+      railties (>= 3.2, < 8.0)
     formatador (0.3.0)
     formtastic (3.1.5)
       actionpack (>= 3.2.13)
@@ -221,7 +251,7 @@ GEM
       formtastic (>= 3.0)
     geckodriver-helper (0.24.0)
       archive-zip (~> 0.7)
-    globalid (0.5.2)
+    globalid (1.0.0)
       activesupport (>= 5.0)
     gravtastic (3.2.6)
     guard (2.18.0)
@@ -265,7 +295,7 @@ GEM
     http-accept (1.7.0)
     http-cookie (1.0.4)
       domain_name (~> 0.5)
-    i18n (1.8.10)
+    i18n (1.9.1)
       concurrent-ruby (~> 1.0)
     i18n_data (0.13.0)
     icalendar (2.7.1)
@@ -275,6 +305,7 @@ GEM
       mini_magick (>= 4.9.5, < 5)
       ruby-vips (>= 2.0.17, < 3)
     io-like (0.3.1)
+    io-wait (0.2.1)
     iso-639 (0.3.5)
     jquery-datatables-rails (3.4.0)
       actionpack (>= 3.1)
@@ -298,14 +329,15 @@ GEM
       rails (>= 4.2.0)
     letter_opener (1.7.0)
       launchy (~> 2.2)
-    letter_opener_web (1.4.0)
-      actionmailer (>= 3.2)
-      letter_opener (~> 1.0)
-      railties (>= 3.2)
+    letter_opener_web (2.0.0)
+      actionmailer (>= 5.2)
+      letter_opener (~> 1.7)
+      railties (>= 5.2)
+      rexml
     listen (3.6.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
-    loofah (2.12.0)
+    loofah (2.13.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
     lumberjack (1.2.8)
@@ -320,9 +352,9 @@ GEM
       open4 (~> 1.3.4)
       rake
     mini_magick (4.11.0)
-    mini_mime (1.1.0)
-    mini_portile2 (2.6.1)
-    minitest (5.14.4)
+    mini_mime (1.1.2)
+    mini_portile2 (2.7.1)
+    minitest (5.15.0)
     momentjs-rails (2.20.1)
       railties (>= 3.1)
     monetize (1.9.4)
@@ -339,12 +371,27 @@ GEM
     multipart-post (2.1.1)
     mysql2 (0.5.3)
     nenv (0.3.0)
+    net-imap (0.2.3)
+      digest
+      net-protocol
+      strscan
+    net-pop (0.1.1)
+      digest
+      net-protocol
+      timeout
+    net-protocol (0.1.2)
+      io-wait
+      timeout
+    net-smtp (0.3.1)
+      digest
+      net-protocol
+      timeout
     netrc (0.11.0)
     next_rails (1.0.4)
       colorize (>= 0.8.1)
     nio4r (2.5.8)
-    nokogiri (1.12.3)
-      mini_portile2 (~> 2.6.1)
+    nokogiri (1.13.1)
+      mini_portile2 (~> 2.7.0)
       racc (~> 1.4)
     notiffany (0.1.3)
       nenv (~> 0.1)
@@ -418,7 +465,7 @@ GEM
     public_suffix (4.0.6)
     puma (4.3.8)
       nio4r (~> 2.0)
-    racc (1.5.2)
+    racc (1.6.0)
     rack (2.2.3)
     rack-openid (1.4.2)
       rack (>= 1.1.0)
@@ -427,41 +474,20 @@ GEM
       rack
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
-    rails (6.1.4)
-      actioncable (= 6.1.4)
-      actionmailbox (= 6.1.4)
-      actionmailer (= 6.1.4)
-      actionpack (= 6.1.4)
-      actiontext (= 6.1.4)
-      actionview (= 6.1.4)
-      activejob (= 6.1.4)
-      activemodel (= 6.1.4)
-      activerecord (= 6.1.4)
-      activestorage (= 6.1.4)
-      activesupport (= 6.1.4)
+    rails (7.0.1)
+      actioncable (= 7.0.1)
+      actionmailbox (= 7.0.1)
+      actionmailer (= 7.0.1)
+      actionpack (= 7.0.1)
+      actiontext (= 7.0.1)
+      actionview (= 7.0.1)
+      activejob (= 7.0.1)
+      activemodel (= 7.0.1)
+      activerecord (= 7.0.1)
+      activestorage (= 7.0.1)
+      activesupport (= 7.0.1)
       bundler (>= 1.15.0)
-      railties (= 6.1.4)
-      sprockets-rails (>= 2.0.0)
-    rails-assets-bootstrap (3.4.1)
-      rails-assets-jquery (>= 1.9.1, < 4)
-    rails-assets-bootstrap-markdown (2.10.0)
-      rails-assets-bootstrap (~> 3)
-    rails-assets-bootstrap-select (1.13.10)
-      rails-assets-bootstrap (>= 3.0.0)
-      rails-assets-jquery (>= 1.9.1, < 4)
-    rails-assets-date.format (1.2.3)
-    rails-assets-holderjs (2.9.6)
-    rails-assets-jquery (3.4.1)
-    rails-assets-jquery-smooth-scroll (2.2.0)
-      rails-assets-jquery (>= 1.7.0)
-    rails-assets-markdown (0.5.0)
-    rails-assets-momentjs (2.22.2)
-    rails-assets-spectrum (1.8.0)
-      rails-assets-jquery (>= 1.7.2)
-    rails-assets-tinycolor (1.4.1)
-    rails-assets-to-markdown (3.1.1)
-    rails-assets-trianglify (1.2.0)
-    rails-assets-waypoints (4.0.1)
+      railties (= 7.0.1)
     rails-controller-testing (1.0.5)
       actionpack (>= 5.0.1.rc1)
       actionview (>= 5.0.1.rc1)
@@ -469,17 +495,18 @@ GEM
     rails-dom-testing (2.0.3)
       activesupport (>= 4.2.0)
       nokogiri (>= 1.6)
-    rails-html-sanitizer (1.3.0)
+    rails-html-sanitizer (1.4.2)
       loofah (~> 2.3)
-    rails-i18n (6.0.0)
+    rails-i18n (7.0.1)
       i18n (>= 0.7, < 2)
-      railties (>= 6.0.0, < 7)
-    railties (6.1.4)
-      actionpack (= 6.1.4)
-      activesupport (= 6.1.4)
+      railties (>= 6.0.0, < 8)
+    railties (7.0.1)
+      actionpack (= 7.0.1)
+      activesupport (= 7.0.1)
       method_source
-      rake (>= 0.13)
+      rake (>= 12.2)
       thor (~> 1.0)
+      zeitwerk (~> 2.5)
     rainbow (3.0.0)
     rake (13.0.6)
     rb-fsevent (0.11.0)
@@ -612,11 +639,13 @@ GEM
       dante (>= 0.2.0)
       multi_json (~> 1.0)
       stripe (> 5, < 6)
+    strscan (3.0.1)
     sysexits (1.2.0)
     temple (0.8.2)
-    thor (1.1.0)
+    thor (1.2.1)
     tilt (2.0.10)
     timecop (0.9.4)
+    timeout (0.2.0)
     transitions (1.2.1)
     ttfunk (1.7.0)
     turbolinks (5.2.1)
@@ -655,7 +684,7 @@ GEM
       chronic (>= 0.6.3)
     xpath (3.2.0)
       nokogiri (~> 1.8)
-    zeitwerk (2.4.2)
+    zeitwerk (2.5.4)
 
 PLATFORMS
   ruby
@@ -728,7 +757,7 @@ DEPENDENCIES
   prawn-qrcode
   prawn-rails
   puma (~> 4.3)
-  rails (~> 6)
+  rails (~> 7)
   rails-assets-bootstrap-markdown!
   rails-assets-bootstrap-select!
   rails-assets-date.format!
@@ -776,7 +805,7 @@ DEPENDENCIES
   whenever
 
 RUBY VERSION
-   ruby 2.5.9p229
+   ruby 3.1.0
 
 BUNDLED WITH
-   1.17.3
+   2.3.3