diff --git a/backend/app/controllers/materials_controller.rb b/backend/app/controllers/materials_controller.rb
index 023a557..77d6402 100644
--- a/backend/app/controllers/materials_controller.rb
+++ b/backend/app/controllers/materials_controller.rb
@@ -54,21 +54,27 @@ class MaterialsController < ApplicationController
     block = MaterialImportBlockMatcher.match_for_sha256(file_sha256)
     return render_material_import_block(block) if block
 
+    uploaded_blob = build_uploaded_material_blob!(file, file_sha256)
     material = nil
-    Material.transaction do
-      tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
-      tag = tag_name.tag
-      tag = Tag.create!(tag_name:, category: :material) unless tag
 
-      material = Material.new(tag:, url:,
-                              created_by_user: current_user,
-                              updated_by_user: current_user)
-      material.file.attach(file) if file
-      apply_file_sha256!(material, file_sha256)
-      material.save!
-      upsert_export_paths!(material)
-      MaterialVersionRecorder.record!(material:, event_type: :create,
-                                      created_by_user: current_user)
+    begin
+      Material.transaction do
+        tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
+        tag = tag_name.tag
+        tag = Tag.create!(tag_name:, category: :material) unless tag
+
+        material = Material.new(tag:, url:,
+                                created_by_user: current_user,
+                                updated_by_user: current_user)
+        material.file.attach(uploaded_blob) if uploaded_blob
+        material.save!
+        upsert_export_paths!(material)
+        MaterialVersionRecorder.record!(material:, event_type: :create,
+                                        created_by_user: current_user)
+      end
+    rescue StandardError
+      uploaded_blob&.purge_later
+      raise
     end
 
     if material
@@ -97,19 +103,30 @@ class MaterialsController < ApplicationController
     block = MaterialImportBlockMatcher.match_for_sha256(file_sha256)
     return render_material_import_block(block) if block
 
-    Material.transaction do
-      MaterialVersionRecorder.ensure_snapshot!(material, created_by_user: current_user)
-      tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
-      tag = tag_name.tag
-      tag = Tag.create!(tag_name:, category: :material) unless tag
+    uploaded_blob = build_uploaded_material_blob!(file, file_sha256)
 
-      material.update!(tag:, url:, updated_by_user: current_user)
-      material.file.attach(file) if file
-      apply_file_sha256!(material, file_sha256)
-      material.file.detach if params.key?(:url) && url.present? && file.blank?
-      upsert_export_paths!(material)
-      MaterialVersionRecorder.record!(material:, event_type: :update,
-                                      created_by_user: current_user)
+    begin
+      Material.transaction do
+        MaterialVersionRecorder.ensure_snapshot!(material, created_by_user: current_user)
+        tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
+        tag = tag_name.tag
+        tag = Tag.create!(tag_name:, category: :material) unless tag
+
+        material.assign_attributes(tag:, url:, updated_by_user: current_user)
+        if uploaded_blob
+          material.file.attach(uploaded_blob)
+          clear_file_suppression!(material)
+        elsif params.key?(:url) && url.present? && file.blank?
+          material.file.detach
+        end
+        material.save!
+        upsert_export_paths!(material)
+        MaterialVersionRecorder.record!(material:, event_type: :update,
+                                        created_by_user: current_user)
+      end
+    rescue StandardError
+      uploaded_blob&.purge_later
+      raise
     end
 
     render json: MaterialRepr.base(material, host: request.base_url)
@@ -220,13 +237,31 @@ class MaterialsController < ApplicationController
            status: :unprocessable_entity
   end
 
-  def apply_file_sha256! material, file_sha256
-    return if file_sha256.blank?
-    return unless material.file.attached?
+  def build_uploaded_material_blob! file, file_sha256
+    return nil unless file
 
-    blob = material.file.blob
-    blob.metadata['sha256'] = file_sha256
-    blob.save! if blob.changed?
+    file.tempfile.rewind
+
+    blob = ActiveStorage::Blob.create_and_upload!(
+        io: file.tempfile,
+        filename: file.original_filename,
+        content_type: file.content_type,
+    )
+
+    if file_sha256.present?
+      blob.metadata['sha256'] = file_sha256
+      blob.save! if blob.changed?
+    end
+
+    blob
+  ensure
+    file.tempfile.rewind if file&.tempfile
+  end
+
+  def clear_file_suppression! material
+    material.file_suppressed_at = nil
+    material.file_suppressed_by_user = nil
+    material.file_suppression_reason = nil
   end
 
   def purge_material_file_snapshot material