re-pushing this, this got merged into master already but i accidentally deleted it when merging two branches

app/controllers/protocols_controller.rb

@@ -601,6 +601,14 @@ class ProtocolsController < ApplicationController
   def protocolsio_import_create
     @protocolsio_too_big = false
     @protocolsio_invalid_file = false
+    @protocolsio_no_file = false
+    if params[:json_file].nil?
+      @protocolsio_no_file = true
+      respond_to do |format|
+        format.js {}
+      end
+      return 0 # return 0 stops the rest of the controller code from executing
+    end
     extension = File.extname(params[:json_file].path)
     file_size = File.size(params[:json_file].path)
     if extension != '.txt' && extension != '.json'

app/views/protocols/import_export/_import_json_protocol_modal.html.erb

@@ -18,6 +18,7 @@
       <div class="modal-body">
 
         <%= file_field_tag 'json_file', accept: '.txt,.json' %>
+        <div id="pio_no_file_error_span"></div>
 
       </div>
       <div class="modal-footer">

app/views/protocols/protocolsio_import_create.js.erb

@@ -1,3 +1,6 @@
+$('#modal-import-json-protocol').on('hidden.bs.modal', function () {
+    $('#pio_no_file_error_span').empty();
+})
 <% if @protocolsio_too_big %>
 $('#modal-import-json-protocol').modal('hide');
 HelperModule.flashAlertMsg(' <%= t('my_modules.protocols.load_from_file_size_error',
@@ -5,6 +8,9 @@ HelperModule.flashAlertMsg(' <%= t('my_modules.protocols.load_from_file_size_err
 <% elsif @protocolsio_invalid_file %>
 $('#modal-import-json-protocol').modal('hide');
 HelperModule.flashAlertMsg(' <%= t('my_modules.protocols.load_from_file_invalid_error') %>','danger');
+<% elsif @protocolsio_no_file %>
+$('#pio_no_file_error_span').addClass('has-error').html('<span class="help-block"> <%= t('teams.parse_sheet.errors.no_file_selected') %></span>');
+<% @protocolsio_no_file = false %>
 <% else %>
   $('#modal-import-json-protocol').modal('hide');
       <% if remotipart_submitted? %> <%# a workaround to a bug with remotipart, that caused alot of headache, courtesy of github.com/dhampik %>