diff --git a/app/controllers/france_connect/particulier_controller.rb b/app/controllers/france_connect/particulier_controller.rb
index 13f41b6f1..5817a3185 100644
--- a/app/controllers/france_connect/particulier_controller.rb
+++ b/app/controllers/france_connect/particulier_controller.rb
@@ -53,7 +53,7 @@ class FranceConnect::ParticulierController < ApplicationController
       if !user.can_france_connect?
         flash.alert = t('errors.messages.france_connect.forbidden_html', reset_link: new_user_password_path)
 
-        render js: ajax_redirect(root_path)
+        redirect_to root_path
       else
         @fci.update(user: user)
         @fci.delete_merge_token!
@@ -63,8 +63,6 @@ class FranceConnect::ParticulierController < ApplicationController
       end
     else
       flash.alert = t('france_connect.particulier.flash.invalid_password')
-
-      render js: helpers.render_flash
     end
   end
 
@@ -112,10 +110,7 @@ class FranceConnect::ParticulierController < ApplicationController
     if @fci.nil? || !@fci.valid_for_merge?
       flash.alert = t('france_connect.particulier.flash.merger_token_expired', application_name: APPLICATION_NAME)
 
-      respond_to do |format|
-        format.html { redirect_to root_path }
-        format.js { render js: ajax_redirect(root_path) }
-      end
+      redirect_to root_path
     end
   end
 
@@ -134,12 +129,7 @@ class FranceConnect::ParticulierController < ApplicationController
 
     user.update_attribute('loged_in_with_france_connect', User.loged_in_with_france_connects.fetch(:particulier))
 
-    redirection_location = stored_location_for(current_user) || root_path(current_user)
-
-    respond_to do |format|
-      format.html { redirect_to redirection_location }
-      format.js { render js: ajax_redirect(root_path) }
-    end
+    redirect_to stored_location_for(current_user) || root_path(current_user)
   end
 
   def redirect_france_connect_error_connection
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index b6f91df67..c45b81052 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -40,77 +40,6 @@ module ApplicationHelper
     tag.div(**html.merge(data: { controller: 'react', react_component_value: name, react_props_value: props.to_json }))
   end
 
-  def render_to_element(selector, partial:, outer: false, locals: {})
-    method = outer ? 'outerHTML' : 'innerHTML'
-    html = escape_javascript(render partial: partial, locals: locals)
-    # rubocop:disable Rails/OutputSafety
-    raw("document.querySelector('#{selector}').#{method} = \"#{html}\";")
-    # rubocop:enable Rails/OutputSafety
-  end
-
-  def append_to_element(selector, partial:, locals: {})
-    html = escape_javascript(render partial: partial, locals: locals)
-    # rubocop:disable Rails/OutputSafety
-    raw("document.querySelector('#{selector}').insertAdjacentHTML('beforeend', \"#{html}\");")
-    # rubocop:enable Rails/OutputSafety
-  end
-
-  def render_flash(timeout: false, sticky: false, fixed: false)
-    if flash.any?
-      html = render_to_element('#flash_messages', partial: 'layouts/flash_messages', locals: { sticky: sticky, fixed: fixed }, outer: true)
-      flash.clear
-      if timeout
-        html += remove_element('#flash_messages', timeout: timeout, inner: true)
-      end
-      html
-    end
-  end
-
-  def remove_element(selector, timeout: 0, inner: false)
-    script = "(function() {";
-    script << "var el = document.querySelector('#{selector}');"
-    method = (inner ? "el.innerHTML = ''" : "el.parentNode.removeChild(el)")
-    if timeout.present? && timeout > 0
-      script << "if (el) { setTimeout(function() { #{method}; }, #{timeout}); }"
-    else
-      script << "if (el) { #{method} };"
-    end
-    script << "})();"
-    # rubocop:disable Rails/OutputSafety
-    raw(script);
-    # rubocop:enable Rails/OutputSafety
-  end
-
-  def show_element(selector)
-    # rubocop:disable Rails/OutputSafety
-    raw("document.querySelector('#{selector}').classList.remove('hidden');")
-    # rubocop:enable Rails/OutputSafety
-  end
-
-  def focus_element(selector)
-    # rubocop:disable Rails/OutputSafety
-    raw("document.querySelector('#{selector}').focus();")
-    # rubocop:enable Rails/OutputSafety
-  end
-
-  def disable_element(selector)
-    # rubocop:disable Rails/OutputSafety
-    raw("document.querySelector('#{selector}').disabled = true;")
-    # rubocop:enable Rails/OutputSafety
-  end
-
-  def enable_element(selector)
-    # rubocop:disable Rails/OutputSafety
-    raw("document.querySelector('#{selector}').disabled = false;")
-    # rubocop:enable Rails/OutputSafety
-  end
-
-  def fire_event(event_name, data)
-    # rubocop:disable Rails/OutputSafety
-    raw("DS.fire('#{event_name}', #{raw(data)});")
-    # rubocop:enable Rails/OutputSafety
-  end
-
   def current_email
     current_user&.email ||
       current_instructeur&.email ||
diff --git a/app/javascript/entrypoints/application.js b/app/javascript/entrypoints/application.js
index 6e3ec2bc6..3143e2dd9 100644
--- a/app/javascript/entrypoints/application.js
+++ b/app/javascript/entrypoints/application.js
@@ -5,17 +5,14 @@ import { Application } from '@hotwired/stimulus';
 import '@gouvfr/dsfr/dist/dsfr.module.js';
 
 import '../shared/activestorage/ujs';
-import '../shared/remote-poller';
-import '../shared/safari-11-file-xhr-workaround';
+import '../shared/safari-11-empty-file-workaround';
 import '../shared/toggle-target';
-import '../shared/ujs-error-handling';
 
 import { registerControllers } from '../shared/stimulus-loader';
 
 import '../new_design/form-validation';
 import '../new_design/procedure-context';
 import '../new_design/procedure-form';
-import '../new_design/spinner';
 import '../new_design/support';
 
 import {
@@ -31,11 +28,7 @@ import {
   acceptEmailSuggestion,
   discardEmailSuggestionBox
 } from '../new_design/user-sign_up';
-import {
-  showFusion,
-  showNewAccount,
-  showNewAccountPasswordConfirmation
-} from '../new_design/fc-fusion';
+import { showFusion, showNewAccount } from '../new_design/fc-fusion';
 
 const application = Application.start();
 registerControllers(application);
@@ -49,7 +42,6 @@ const DS = {
   showImportJustificatif,
   showFusion,
   showNewAccount,
-  showNewAccountPasswordConfirmation,
   replaceSemicolonByComma,
   acceptEmailSuggestion,
   discardEmailSuggestionBox
diff --git a/app/javascript/new_design/fc-fusion.js b/app/javascript/new_design/fc-fusion.js
index e9d4b7628..3ef0fce4e 100644
--- a/app/javascript/new_design/fc-fusion.js
+++ b/app/javascript/new_design/fc-fusion.js
@@ -3,17 +3,11 @@ import { show, hide } from '@utils';
 export function showFusion() {
   show(document.querySelector('.fusion'));
   hide(document.querySelector('.new-account'));
-  hide(document.querySelector('.new-account-password-confirmation'));
+  hide(document.querySelector('#new-account-password-confirmation'));
 }
 
 export function showNewAccount() {
   hide(document.querySelector('.fusion'));
   show(document.querySelector('.new-account'));
-  hide(document.querySelector('.new-account-password-confirmation'));
-}
-
-export function showNewAccountPasswordConfirmation() {
-  hide(document.querySelector('.fusion'));
-  hide(document.querySelector('.new-account'));
-  show(document.querySelector('.new-account-password-confirmation'));
+  hide(document.querySelector('#new-account-password-confirmation'));
 }
diff --git a/app/javascript/new_design/spinner.js b/app/javascript/new_design/spinner.js
deleted file mode 100644
index 8b1fbac3e..000000000
--- a/app/javascript/new_design/spinner.js
+++ /dev/null
@@ -1,13 +0,0 @@
-import { show, hide, delegate } from '@utils';
-
-function showSpinner() {
-  [...document.querySelectorAll('.spinner')].forEach(show);
-}
-
-function hideSpinner() {
-  [...document.querySelectorAll('.spinner')].forEach(hide);
-}
-
-delegate('ajax:complete', '[data-spinner]', hideSpinner);
-delegate('ajax:stopped', '[data-spinner]', hideSpinner);
-delegate('ajax:send', '[data-spinner]', showSpinner);
diff --git a/app/javascript/shared/remote-poller.js b/app/javascript/shared/remote-poller.js
deleted file mode 100644
index 77984c900..000000000
--- a/app/javascript/shared/remote-poller.js
+++ /dev/null
@@ -1,101 +0,0 @@
-import { httpRequest, delegate } from '@utils';
-
-addEventListener('DOMContentLoaded', () => {
-  attachementPoller.deactivate();
-  exportPoller.deactivate();
-
-  const attachments = document.querySelectorAll('[data-attachment-poll-url]');
-  const exports = document.querySelectorAll('[data-export-poll-url]');
-
-  for (let { dataset } of attachments) {
-    attachementPoller.add(dataset.attachmentPollUrl);
-  }
-
-  for (let { dataset } of exports) {
-    exportPoller.add(dataset.exportPollUrl);
-  }
-});
-
-addEventListener('attachment:update', ({ detail: { url } }) => {
-  attachementPoller.add(url);
-});
-
-addEventListener('export:update', ({ detail: { url } }) => {
-  exportPoller.add(url);
-});
-
-delegate('click', '[data-attachment-refresh]', (event) => {
-  event.preventDefault();
-  attachementPoller.check();
-});
-
-// Periodically check the state of a set of URLs.
-//
-// Each time the given URL is requested, the matching `show.js.erb` view is rendered,
-// causing the state to be refreshed.
-//
-// This is used mainly to refresh attachments during the anti-virus check,
-// but also to refresh the state of a pending spreadsheet export.
-class RemotePoller {
-  urls = new Set();
-  timeout;
-  checks = 0;
-
-  constructor(settings = {}) {
-    this.interval = settings.interval;
-    this.maxChecks = settings.maxChecks;
-  }
-
-  get isEnabled() {
-    return this.checks <= this.maxChecks;
-  }
-
-  get isActive() {
-    return this.timeout !== undefined;
-  }
-
-  add(url) {
-    if (this.isEnabled) {
-      if (!this.isActive) {
-        this.activate();
-      }
-      this.urls.add(url);
-    }
-  }
-
-  check() {
-    let urls = this.urls;
-    this.reset();
-    for (let url of urls) {
-      // Start the request. The JS payload in the response will update the page.
-      // (Errors are ignored, because background tasks shouldn't report errors to the user.)
-      httpRequest(url)
-        .js()
-        .catch(() => {});
-    }
-  }
-
-  activate() {
-    clearTimeout(this.timeout);
-    this.timeout = setTimeout(() => {
-      this.checks++;
-      this.currentInterval = this.interval * 1.5;
-      this.check();
-    }, this.currentInterval);
-  }
-
-  deactivate() {
-    this.checks = 0;
-    this.currentInterval = this.interval;
-    this.reset();
-  }
-
-  reset() {
-    clearTimeout(this.timeout);
-    this.urls = new Set();
-    this.timeout = undefined;
-  }
-}
-
-const attachementPoller = new RemotePoller({ interval: 3000, maxChecks: 5 });
-const exportPoller = new RemotePoller({ interval: 6000, maxChecks: 10 });
diff --git a/app/javascript/shared/safari-11-empty-file-workaround.ts b/app/javascript/shared/safari-11-empty-file-workaround.ts
new file mode 100644
index 000000000..19f689049
--- /dev/null
+++ b/app/javascript/shared/safari-11-empty-file-workaround.ts
@@ -0,0 +1,36 @@
+// iOS 11.3 Safari / macOS Safari 11.1 empty <input type="file"> XHR bug workaround.
+// This should work with every modern browser which supports ES5 (including IE9).
+// https://stackoverflow.com/questions/49614091/safari-11-1-ajax-xhr-form-submission-fails-when-inputtype-file-is-empty
+// https://github.com/rails/rails/issues/32440
+
+document.documentElement.addEventListener(
+  'turbo:before-fetch-request',
+  (event) => {
+    const target = event.target as Element;
+    const inputs = target.querySelectorAll<HTMLInputElement>(
+      'input[type="file"]:not([disabled])'
+    );
+    for (const input of inputs) {
+      if (input.files?.length == 0) {
+        input.setAttribute('data-safari-temp-disabled', 'true');
+        input.setAttribute('disabled', '');
+      }
+    }
+  }
+);
+
+document.documentElement.addEventListener(
+  'turbo:before-fetch-response',
+  (event) => {
+    const target = event.target as Element;
+    const inputs = target.querySelectorAll(
+      'input[type="file"][data-safari-temp-disabled]'
+    );
+    for (const input of inputs) {
+      input.removeAttribute('data-safari-temp-disabled');
+      input.removeAttribute('disabled');
+    }
+  }
+);
+
+export {};
diff --git a/app/javascript/shared/safari-11-file-xhr-workaround.js b/app/javascript/shared/safari-11-file-xhr-workaround.js
deleted file mode 100644
index 2d7fa2707..000000000
--- a/app/javascript/shared/safari-11-file-xhr-workaround.js
+++ /dev/null
@@ -1,26 +0,0 @@
-// iOS 11.3 Safari / macOS Safari 11.1 empty <input type="file"> XHR bug workaround.
-// This should work with every modern browser which supports ES5 (including IE9).
-// https://stackoverflow.com/questions/49614091/safari-11-1-ajax-xhr-form-submission-fails-when-inputtype-file-is-empty
-// https://github.com/rails/rails/issues/32440
-
-document.addEventListener('ajax:before', function (e) {
-  let inputs = e.target.querySelectorAll('input[type="file"]:not([disabled])');
-  inputs.forEach(function (input) {
-    if (input.files.length > 0) {
-      return;
-    }
-    input.setAttribute('data-safari-temp-disabled', 'true');
-    input.setAttribute('disabled', '');
-  });
-});
-
-// You should call this by yourself when you aborted an ajax request by stopping a event in ajax:before hook.
-document.addEventListener('ajax:beforeSend', function (e) {
-  let inputs = e.target.querySelectorAll(
-    'input[type="file"][data-safari-temp-disabled]'
-  );
-  inputs.forEach(function (input) {
-    input.removeAttribute('data-safari-temp-disabled');
-    input.removeAttribute('disabled');
-  });
-});
diff --git a/app/javascript/shared/ujs-error-handling.js b/app/javascript/shared/ujs-error-handling.js
deleted file mode 100644
index 495dc0e06..000000000
--- a/app/javascript/shared/ujs-error-handling.js
+++ /dev/null
@@ -1,8 +0,0 @@
-// For links and requests done through rails-ujs (mostly data-remote links),
-// redirect to the sign-in page when the server responds '401 Unauthorized'.
-document.addEventListener('ajax:error', (event) => {
-  const [, , xhr] = event.detail;
-  if (xhr && xhr.status == 401) {
-    location.reload(); // reload whole page so Devise will redirect to sign-in
-  }
-});
diff --git a/app/views/administrateurs/experts_procedures/index.html.haml b/app/views/administrateurs/experts_procedures/index.html.haml
index a4c658504..68ebef395 100644
--- a/app/views/administrateurs/experts_procedures/index.html.haml
+++ b/app/views/administrateurs/experts_procedures/index.html.haml
@@ -16,7 +16,7 @@
         url: allow_expert_review_admin_procedure_path(@procedure),
         html: { class: 'form procedure-form__column--form no-background' } do |f|
         %label.toggle-switch
-          = f.check_box :allow_expert_review, class: 'toggle-switch-checkbox', onchange: 'this.form.submit()'
+          = f.check_box :allow_expert_review, class: 'toggle-switch-checkbox', onchange: 'this.form.requestSubmit()'
           %span.toggle-switch-control.round
           %span.toggle-switch-label.on
           %span.toggle-switch-label.off
@@ -30,7 +30,7 @@
           url: experts_require_administrateur_invitation_admin_procedure_path(@procedure),
           html: { class: 'form procedure-form__column--form no-background' } do |f|
           %label.toggle-switch
-            = f.check_box :experts_require_administrateur_invitation, class: 'toggle-switch-checkbox', onchange: 'this.form.submit()'
+            = f.check_box :experts_require_administrateur_invitation, class: 'toggle-switch-checkbox', onchange: 'this.form.requestSubmit()'
             %span.toggle-switch-control.round
             %span.toggle-switch-label.on
             %span.toggle-switch-label.off
@@ -76,12 +76,11 @@
                   %td.text-center
                     = form_for expert_procedure,
                       url: admin_procedure_expert_path(id: expert_procedure),
-                      remote: true,
                       method: :put,
-                      authenticity_token: true,
+                      data: { turbo: true },
                       html: { class: 'form procedure-form__column--form no-background' } do |f|
                       %label.toggle-switch
-                        = f.check_box :allow_decision_access, class: 'toggle-switch-checkbox', onchange: 'this.form.submit()'
+                        = f.check_box :allow_decision_access, class: 'toggle-switch-checkbox', onchange: 'this.form.requestSubmit()'
                         %span.toggle-switch-control.round
                         %span.toggle-switch-label.on
                         %span.toggle-switch-label.off
diff --git a/app/views/france_connect/particulier/_password_confirmation.html.haml b/app/views/france_connect/particulier/_password_confirmation.html.haml
index eda3ea1bc..0fa778734 100644
--- a/app/views/france_connect/particulier/_password_confirmation.html.haml
+++ b/app/views/france_connect/particulier/_password_confirmation.html.haml
@@ -3,7 +3,7 @@
   %br
   = t('.fill_in_password')
 
-= form_tag france_connect_particulier_merge_with_existing_account_path, remote: true, class: 'mt-2 form fconnect-form' do
+= form_tag france_connect_particulier_merge_with_existing_account_path, data: { turbo: true }, class: 'mt-2 form fconnect-form' do
   = hidden_field_tag :merge_token, merge_token
   = hidden_field_tag :email, email
   = label_tag :password, t('views.registrations.new.password_label', min_length: 8)
diff --git a/app/views/france_connect/particulier/merge.html.haml b/app/views/france_connect/particulier/merge.html.haml
index ce8fedec8..aeb4ec2bb 100644
--- a/app/views/france_connect/particulier/merge.html.haml
+++ b/app/views/france_connect/particulier/merge.html.haml
@@ -19,9 +19,9 @@
   .fusion.hidden
     %p= t('.title_fill_in_password')
 
-    = form_tag france_connect_particulier_merge_with_existing_account_path, remote: true, class: 'mt-2 form fconnect-form' do
-      = hidden_field_tag :merge_token, @fci.merge_token
-      = hidden_field_tag :email, @fci.email_france_connect
+    = form_tag france_connect_particulier_merge_with_existing_account_path, data: { turbo: true }, class: 'mt-2 form fconnect-form' do
+      = hidden_field_tag :merge_token, @fci.merge_token, id: dom_id(@fci, :fusion_merge_token)
+      = hidden_field_tag :email, @fci.email_france_connect, id: dom_id(@fci, :fusion_email)
 
       = label_tag :password, t('views.registrations.new.password_label', min_length: 8)
       = password_field_tag :password, nil, autocomplete: 'current-password', class: 'mb-1'
@@ -36,11 +36,11 @@
   .new-account.hidden
     %p= t('.title_fill_in_email', application_name: APPLICATION_NAME)
 
-    = form_tag france_connect_particulier_merge_with_new_account_path, remote: true, class: 'mt-2 form' do
-      = hidden_field_tag :merge_token, @fci.merge_token
-      = label_tag :email, t('views.registrations.new.email_label')
-      = email_field_tag :email, "", required: true
+    = form_tag france_connect_particulier_merge_with_new_account_path, data: { turbo: true }, class: 'mt-2 form' do
+      = hidden_field_tag :merge_token, @fci.merge_token, id: dom_id(@fci, :new_account_merge_token)
+      = label_tag :email, t('views.registrations.new.email_label'), for: dom_id(@fci, :new_account_email)
+      = email_field_tag :email, "", required: true, id: dom_id(@fci, :new_account_email)
       = submit_tag t('.button_use_this_email'), class: 'button primary'
 
 
-  .new-account-password-confirmation.hidden
+  #new-account-password-confirmation.hidden
diff --git a/app/views/france_connect/particulier/merge_with_existing_account.turbo_stream.haml b/app/views/france_connect/particulier/merge_with_existing_account.turbo_stream.haml
new file mode 100644
index 000000000..e69de29bb
diff --git a/app/views/france_connect/particulier/merge_with_new_account.js.erb b/app/views/france_connect/particulier/merge_with_new_account.js.erb
deleted file mode 100644
index cea1ca67a..000000000
--- a/app/views/france_connect/particulier/merge_with_new_account.js.erb
+++ /dev/null
@@ -1,3 +0,0 @@
-<%= render_to_element('.new-account-password-confirmation', partial: 'password_confirmation', locals: { email: @email, merge_token: @merge_token }) %>
-
-DS.showNewAccountPasswordConfirmation();
diff --git a/app/views/france_connect/particulier/merge_with_new_account.turbo_stream.haml b/app/views/france_connect/particulier/merge_with_new_account.turbo_stream.haml
new file mode 100644
index 000000000..7d14ef01a
--- /dev/null
+++ b/app/views/france_connect/particulier/merge_with_new_account.turbo_stream.haml
@@ -0,0 +1,4 @@
+= turbo_stream.update 'new-account-password-confirmation', partial: 'password_confirmation', locals: { email: @email, merge_token: @merge_token }
+= turbo_stream.hide_all '.fusion'
+= turbo_stream.hide_all '.new-account'
+= turbo_stream.show 'new-account-password-confirmation'
diff --git a/app/views/instructeurs/archives/create.js.haml b/app/views/instructeurs/archives/create.js.haml
deleted file mode 100644
index 7fe9f7f0b..000000000
--- a/app/views/instructeurs/archives/create.js.haml
+++ /dev/null
@@ -1 +0,0 @@
-= render_flash(sticky: true)
diff --git a/spec/controllers/france_connect/particulier_controller_spec.rb b/spec/controllers/france_connect/particulier_controller_spec.rb
index fd6c2cd27..76bbae30d 100644
--- a/spec/controllers/france_connect/particulier_controller_spec.rb
+++ b/spec/controllers/france_connect/particulier_controller_spec.rb
@@ -198,7 +198,7 @@ describe FranceConnect::ParticulierController, type: :controller do
     let(:merge_token) { fci.create_merge_token! }
     let(:email) { 'EXISTING_account@a.com ' }
     let(:password) { 'my-s3cure-p4ssword' }
-    let(:format) { :js }
+    let(:format) { :turbo_stream }
 
     subject { post :merge_with_existing_account, params: { merge_token: merge_token, email: email, password: password }, format: format }
 
@@ -309,7 +309,7 @@ describe FranceConnect::ParticulierController, type: :controller do
     let(:fci) { FranceConnectInformation.create!(user_info) }
     let(:merge_token) { fci.create_merge_token! }
     let(:email) { ' Account@a.com ' }
-    let(:format) { :js }
+    let(:format) { :turbo_stream }
 
     subject { post :merge_with_new_account, params: { merge_token: merge_token, email: email }, format: format }
 
@@ -323,7 +323,7 @@ describe FranceConnect::ParticulierController, type: :controller do
         expect(fci.user.email).to eq(email.downcase.strip)
         expect(fci.merge_token).to be_nil
         expect(controller.current_user).to eq(fci.user)
-        expect(response.body).to include("window.location.href='/'")
+        expect(response).to redirect_to(root_path)
       end
     end
 
diff --git a/spec/system/france_connect/france_connect_particulier_spec.rb b/spec/system/france_connect/france_connect_particulier_spec.rb
index 33ad0aae1..f6cad87ee 100644
--- a/spec/system/france_connect/france_connect_particulier_spec.rb
+++ b/spec/system/france_connect/france_connect_particulier_spec.rb
@@ -83,7 +83,7 @@ describe 'France Connect Particulier Connexion' do
 
                 expect(page).to have_css('#password-for-another-account', visible: true)
 
-                within '.new-account-password-confirmation' do
+                within '#new-account-password-confirmation' do
                   fill_in 'password', with: 'my-s3cure-p4ssword'
                   click_on 'Fusionner les comptes'
                 end