Paypal Plus Payment Plugin error message

-- HikaShop version -- : HikaShop Business: 4.4.3 & HikaMarket Multivendor: 4.0.0
-- Joomla version -- : 4.0.3
-- PHP version -- : 7.4.23
-- Browser(s) name and version -- : Google Chrome
-- Error-message(debug-mod must be tuned on) -- : Call to undefined method Joomla \ CMS \ Application \ AdministratorApplication :: isAdmin ()
Call stack
# Function Location
1 () JROOT / plugins / hikashoppayment / paypalplus / paypalplus.php: 557
2 plgHikashoppaymentPaypalplus-> onHikashopBeforeDisplayView () JROOT / libraries / src / Plugin / CMSPlugin.php: 285
3 Joomla \ CMS \ Plugin \ CMSPlugin-> Joomla \ CMS \ Plugin \ {closure} () JROOT / libraries / vendor / joomla / event / src / Dispatcher.php: 486
4 Joomla \ Event \ Dispatcher-> dispatch () JROOT / libraries / src / Application / EventAware.php: 111
5 Joomla \ CMS \ Application \ WebApplication-> triggerEvent () JROOT / administrator / components / com_hikashop / helpers / helper.php: 2529
6 hikashopView-> display () JROOT / administrator / components / com_hikashop / views / plugins / view.html.php: 23
7 PluginsViewPlugins-> display () JROOT / libraries / src / MVC / Controller / BaseController.php: 692
8 Joomla \ CMS \ MVC \ Controller \ BaseController-> display () JROOT / administrator / components / com_hikashop / helpers / helper.php: 2302
9 hikashopController-> display () JROOT / administrator / components / com_hikashop / controllers / plugins.php: 159
10 PluginsController-> listing () JROOT / libraries / src / MVC / Controller / BaseController.php: 730
11 Joomla \ CMS \ MVC \ Controller \ BaseController-> execute () JROOT / administrator / components / com_hikashop / helpers / helper.php: 2280
12 hikashopController-> execute () JROOT / administrator / components / com_hikashop / hikashop.php: 75
13 require_once () JROOT / libraries / src / Dispatcher / LegacyComponentDispatcher.php: 69
14 Joomla \ CMS \ Dispatcher \ LegacyComponentDispatcher :: Joomla \ CMS \ Dispatcher \ {closure} () JROOT / libraries / src / Dispatcher / LegacyComponentDispatcher.php: 71
15 Joomla \ CMS \ Dispatcher \ LegacyComponentDispatcher-> dispatch () JROOT / libraries / src / Component / ComponentHelper.php: 389
16 Joomla \ CMS \ Component \ ComponentHelper :: renderComponent () JROOT / libraries / src / Application / AdministratorApplication.php: 143
17 Joomla \ CMS \ Application \ AdministratorApplication-> dispatch () JROOT / libraries / src / Application / AdministratorApplication.php: 186
18 Joomla \ CMS \ Application \ AdministratorApplication-> doExecute () JROOT / libraries / src / Application / CMSApplication.php: 278
19 Joomla \ CMS \ Application \ CMSApplication-> execute () JROOT / administrator / includes / app.php: 63
20 require_once () JROOT / administrator / index.php: 32

Hello Support-Team,
I have the following problem:

When I activate the Hikashop Paypal Plus Payment Plugin, I can no longer access the payment methods in the backend. The following error message appears:

Call to undefined method Joomla \ CMS \ Application \ AdministratorApplication :: isAdmin ()

The same error message appears in the frontend.
Can you help me? (I'm not a programmer)

Thanks very much

Hi Mohamed,
everything went great and works again.
Thanks very much.

Kind regards
Stergios