In the error.log file it is showing the following error:-
[Wed Jul 19 16:39:40.453520 2023] [php:error] [pid 20479] [client 42.109.206.25:14126] PHP Fatal error: Uncaught Error: Class “PKPApplication” not found in /var/www/html/ops/cache/t_compile/0d613bc74e20f5bad4fd6e882abf14a1b3167edd^40904e1188cd43a9d1a1b6c8600463d2d9ed96bd_0.app.managementcontext.tpl.php:90\nStack trace:\n#0 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(248): Block_106766861264b7b19a885278_79499954->callBlock(Object(Smarty_Internal_Template))\n#1 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(184): Smarty_Internal_Runtime_Inheritance->callBlock(Object(Block_106766861264b7b19a885278_79499954), Object(Smarty_Internal_Template))\n#2 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(186): Smarty_Internal_Runtime_Inheritance->process(Object(Smarty_Internal_Template), Object(Block_106766861264b7b19a885278_79499954), Object(Block_195778527964b7b19a8ad762_47553063))\n#3 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(156): Smarty_Internal_Runtime_Inheritance->process(Object(Smarty_Internal_Template), Object(Block_195778527964b7b19a8ad762_47553063))\n#4 /var/www/html/ops/cache/t_compile/0d613bc74e20f5bad4fd6e882abf14a1b3167edd^164bd5a4f3891532cf93e9d19911fe9cb3308efd_0.app.layoutsbackend.tpl.php(238): Smarty_Internal_Runtime_Inheritance->instanceBlock(Object(Smarty_Internal_Template), ‘Block_195778527…’, ‘page’)\n#5 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_64b7b19a8b20e9_14901595(Object(Smarty_Internal_Template))\n#6 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode(Object(Smarty_Internal_Template))\n#7 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(217): Smarty_Template_Compiled->render(Object(Smarty_Internal_Template))\n#8 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(386): Smarty_Internal_Template->render()\n#9 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(116): Smarty_Internal_Template->_subTemplateRender(‘layouts/backend…’, NULL, ‘0d613bc74e20f5b…’, 0, 3600, Array, 2, false, NULL, NULL)\n#10 /var/www/html/ops/cache/t_compile/0d613bc74e20f5bad4fd6e882abf14a1b3167edd^40904e1188cd43a9d1a1b6c8600463d2d9ed96bd_0.app.managementcontext.tpl.php(31): Smarty_Internal_Runtime_Inheritance->endChild(Object(Smarty_Internal_Template), ‘layouts/backend…’)\n#11 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_64b7b19a88ecb7_22092130(Object(Smarty_Internal_Template))\n#12 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode(Object(Smarty_Internal_Template))\n#13 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(217): Smarty_Template_Compiled->render(Object(Smarty_Internal_Template))\n#14 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_templatebase.php(238): Smarty_Internal_Template->render(false, 1)\n#15 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_templatebase.php(134): Smarty_Internal_TemplateBase->_execute(Object(Smarty_Internal_Template), NULL, ‘0d613bc74e20f5b…’, NULL, 1)\n#16 /var/www/html/ops/lib/pkp/classes/template/PKPTemplateManager.php(1325): Smarty_Internal_TemplateBase->display(‘management/cont…’, NULL, ‘0d613bc74e20f5b…’, NULL)\n#17 /var/www/html/ops/lib/pkp/pages/management/ManagementHandler.php(168): PKP\template\PKPTemplateManager->display(‘management/cont…’)\n#18 /var/www/html/ops/lib/pkp/pages/management/ManagementHandler.php(87): PKP\pages\management\ManagementHandler->context(Array, Object(APP\core\Request))\n#19 [internal function]: PKP\pages\management\ManagementHandler->settings(Array, Object(APP\core\Request))\n#20 /var/www/html/ops/lib/pkp/classes/core/PKPRouter.php(334): call_user_func(Array, Array, Object(APP\core\Request))\n#21 /var/www/html/ops/lib/pkp/classes/core/PKPPageRouter.php(277): PKP\core\PKPRouter->_authorizeInitializeAndCallRequest(Array, Object(APP\core\Request), Array, false)\n#22 /var/www/html/ops/lib/pkp/classes/core/Dispatcher.php(165): PKP\core\PKPPageRouter->route(Object(APP\core\Request))\n#23 /var/www/html/ops/lib/pkp/classes/core/PKPApplication.php(373): PKP\core\Dispatcher->dispatch(Object(APP\core\Request))\n#24 /var/www/html/ops/index.php(21): PKP\core\PKPApplication->execute()\n#25 {main}\n thrown in /var/www/html/ops/cache/t_compile/0d613bc74e20f5bad4fd6e882abf14a1b3167edd^40904e1188cd43a9d1a1b6c8600463d2d9ed96bd_0.app.managementcontext.tpl.php on line 90, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45
[Wed Jul 19 16:39:45.511376 2023] [php:warn] [pid 20475] [client 42.109.206.25:14131] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/login?source=%2Fops%2Findex.php%2F1%2Fmanagement%2Fsettings%2Fwebsite%3Fr%3D64b7b7aa09b45
[Wed Jul 19 16:39:45.541281 2023] [php:warn] [pid 20475] [client 42.109.206.25:14131] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/login?source=%2Fops%2Findex.php%2F1%2Fmanagement%2Fsettings%2Fwebsite%3Fr%3D64b7b7aa09b45
[Wed Jul 19 16:39:45.543640 2023] [php:warn] [pid 20475] [client 42.109.206.25:14131] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/login?source=%2Fops%2Findex.php%2F1%2Fmanagement%2Fsettings%2Fwebsite%3Fr%3D64b7b7aa09b45
[Wed Jul 19 16:39:46.410127 2023] [php:warn] [pid 20475] [client 42.109.206.25:14131] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45
[Wed Jul 19 16:39:46.410902 2023] [php:warn] [pid 20553] [client 42.109.206.25:14132] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45
[Wed Jul 19 16:39:46.720589 2023] [php:warn] [pid 20468] [client 42.109.206.25:14134] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45
[Wed Jul 19 16:39:46.743678 2023] [php:warn] [pid 20478] [client 42.109.206.25:14133] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45
[Wed Jul 19 16:39:46.743754 2023] [php:warn] [pid 20552] [client 42.109.206.25:14135] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45
[Wed Jul 19 16:39:46.842462 2023] [php:warn] [pid 20552] [client 42.109.206.25:14135] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45
[Wed Jul 19 16:39:47.879741 2023] [php:warn] [pid 20468] [client 42.109.206.25:14134] PHP Warning: Trying to access array offset on value of type null in /var/www/html/ops/plugins/themes/default/DefaultThemePlugin.php on line 188, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45
[Wed Jul 19 16:39:48.204401 2023] [php:error] [pid 20468] [client 42.109.206.25:14134] PHP Fatal error: Uncaught Error: Class “PKPApplication” not found in /var/www/html/ops/cache/t_compile/0d613bc74e20f5bad4fd6e882abf14a1b3167edd^40904e1188cd43a9d1a1b6c8600463d2d9ed96bd_0.app.managementcontext.tpl.php:90\nStack trace:\n#0 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(248): Block_106766861264b7b19a885278_79499954->callBlock(Object(Smarty_Internal_Template))\n#1 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(184): Smarty_Internal_Runtime_Inheritance->callBlock(Object(Block_106766861264b7b19a885278_79499954), Object(Smarty_Internal_Template))\n#2 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(186): Smarty_Internal_Runtime_Inheritance->process(Object(Smarty_Internal_Template), Object(Block_106766861264b7b19a885278_79499954), Object(Block_195778527964b7b19a8ad762_47553063))\n#3 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(156): Smarty_Internal_Runtime_Inheritance->process(Object(Smarty_Internal_Template), Object(Block_195778527964b7b19a8ad762_47553063))\n#4 /var/www/html/ops/cache/t_compile/0d613bc74e20f5bad4fd6e882abf14a1b3167edd^164bd5a4f3891532cf93e9d19911fe9cb3308efd_0.app.layoutsbackend.tpl.php(238): Smarty_Internal_Runtime_Inheritance->instanceBlock(Object(Smarty_Internal_Template), ‘Block_195778527…’, ‘page’)\n#5 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_64b7b19a8b20e9_14901595(Object(Smarty_Internal_Template))\n#6 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode(Object(Smarty_Internal_Template))\n#7 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(217): Smarty_Template_Compiled->render(Object(Smarty_Internal_Template))\n#8 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(386): Smarty_Internal_Template->render()\n#9 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_runtime_inheritance.php(116): Smarty_Internal_Template->_subTemplateRender(‘layouts/backend…’, NULL, ‘0d613bc74e20f5b…’, 0, 3600, Array, 2, false, NULL, NULL)\n#10 /var/www/html/ops/cache/t_compile/0d613bc74e20f5bad4fd6e882abf14a1b3167edd^40904e1188cd43a9d1a1b6c8600463d2d9ed96bd_0.app.managementcontext.tpl.php(31): Smarty_Internal_Runtime_Inheritance->endChild(Object(Smarty_Internal_Template), ‘layouts/backend…’)\n#11 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_64b7b19a88ecb7_22092130(Object(Smarty_Internal_Template))\n#12 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode(Object(Smarty_Internal_Template))\n#13 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(217): Smarty_Template_Compiled->render(Object(Smarty_Internal_Template))\n#14 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_templatebase.php(238): Smarty_Internal_Template->render(false, 1)\n#15 /var/www/html/ops/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_templatebase.php(134): Smarty_Internal_TemplateBase->_execute(Object(Smarty_Internal_Template), NULL, ‘0d613bc74e20f5b…’, NULL, 1)\n#16 /var/www/html/ops/lib/pkp/classes/template/PKPTemplateManager.php(1325): Smarty_Internal_TemplateBase->display(‘management/cont…’, NULL, ‘0d613bc74e20f5b…’, NULL)\n#17 /var/www/html/ops/lib/pkp/pages/management/ManagementHandler.php(168): PKP\template\PKPTemplateManager->display(‘management/cont…’)\n#18 /var/www/html/ops/lib/pkp/pages/management/ManagementHandler.php(87): PKP\pages\management\ManagementHandler->context(Array, Object(APP\core\Request))\n#19 [internal function]: PKP\pages\management\ManagementHandler->settings(Array, Object(APP\core\Request))\n#20 /var/www/html/ops/lib/pkp/classes/core/PKPRouter.php(334): call_user_func(Array, Array, Object(APP\core\Request))\n#21 /var/www/html/ops/lib/pkp/classes/core/PKPPageRouter.php(277): PKP\core\PKPRouter->_authorizeInitializeAndCallRequest(Array, Object(APP\core\Request), Array, false)\n#22 /var/www/html/ops/lib/pkp/classes/core/Dispatcher.php(165): PKP\core\PKPPageRouter->route(Object(APP\core\Request))\n#23 /var/www/html/ops/lib/pkp/classes/core/PKPApplication.php(373): PKP\core\Dispatcher->dispatch(Object(APP\core\Request))\n#24 /var/www/html/ops/index.php(21): PKP\core\PKPApplication->execute()\n#25 {main}\n thrown in /var/www/html/ops/cache/t_compile/0d613bc74e20f5bad4fd6e882abf14a1b3167edd^40904e1188cd43a9d1a1b6c8600463d2d9ed96bd_0.app.managementcontext.tpl.php on line 90, referer: http://18.191.251.236/ops/index.php/1/management/settings/website?r=64b7b7aa09b45