Unable to complete submission getting stuck stage 3

hi i have posted this before but up till this time I didn’t get any good response, it happens that i am getting complaints from authors who were trying to submit their articles on our journal system, we run an online version of the OJS, at first I thought its the network of where they were, but I decided to give it a trial and I discover that when they to the stage three of the submission process after entering all necessary information like keywords e.t.c. and click on save to continue it get stuck and won’t eventually submit, please anyone who can help solve this issue: below is the error log:
[14-Dec-2022 17:38:33 Africa/Lagos] PHP Fatal error: Uncaught Error: Call to a member function getLocalizedTitle() on null in /home/wnjmscom/public_html/journal/lib/pkp/controllers/grid/notifications/NotificationsGridCellProvider.inc.php:157
Stack trace:
#0 /home/wnjmscom/public_html/journal/lib/pkp/controllers/grid/notifications/NotificationsGridCellProvider.inc.php(44): NotificationsGridCellProvider->_getTitle(Object(Notification))
#1 /home/wnjmscom/public_html/journal/lib/pkp/classes/controllers/grid/GridCellProvider.inc.php(56): NotificationsGridCellProvider->getCellActions(Object(Request), Object(GridRow), Object(GridColumn))
#2 /home/wnjmscom/public_html/journal/lib/pkp/classes/controllers/grid/GridHandler.inc.php(1104): GridCellProvider->render(Object(Request), Object(GridRow), Object(GridColumn))
#3 /home/wnjmscom/public_html/journal/lib/pkp/classes/controllers/grid/GridHandler.inc.php(1011): GridHandler->_renderCellInternally(Object(Request), Object(GridRow), Object(GridColumn))
#4 /home/wnjmscom/public_html/journal/lib/pkp/classes/controllers/grid/GridHandler.inc.php(988): GridHandler->renderRowInternally(Object(Request), Object(GridRow))
#5 /home/wnjmscom/public_html/journal/lib/pkp/classes/controllers/grid/GridHandler.inc.php(1033): GridHandler->renderRowsInternally(Object(Request), Array)
#6 /home/wnjmscom/public_html/journal/lib/pkp/classes/controllers/grid/GridHandler.inc.php(923): GridHandler->renderGridBodyPartsInternally(Object(Request))
#7 /home/wnjmscom/public_html/journal/lib/pkp/classes/controllers/grid/GridHandler.inc.php(643): GridHandler->doSpecificFetchGridActions(Array, Object(Request), Object(TemplateManager))
#8 /home/wnjmscom/public_html/journal/lib/pkp/classes/core/PKPRouter.inc.php(395): GridHandler->fetchGrid(Array, Object(Request))
#9 /home/wnjmscom/public_html/journal/lib/pkp/classes/core/PKPComponentRouter.inc.php(257): PKPRouter->_authorizeInitializeAndCallRequest(Array, Object(Request), Array)
#10 /home/wnjmscom/public_html/journal/lib/pkp/classes/core/Dispatcher.inc.php(144): PKPComponentRouter->route(Object(Request))
#11 /home/wnjmscom/public_html/journal/lib/pkp/classes/core/PKPApplication.inc.php(362): Dispatcher->dispatch(Object(Request))
#12 /home/wnjmscom/public_html/journal/index.php(68): PKPApplication->execute()
#13 {main}
thrown in /home/wnjmscom/public_html/journal/lib/pkp/controllers/grid/notifications/NotificationsGridCellProvider.inc.php on line 157
[14-Dec-2022 19:28:45 Africa/Lagos] PHP Fatal error: Uncaught Error: Call to a member function getFullName() on null in /home/wnjmscom/public_html/journal/lib/pkp/classes/submission/reviewAssignment/ReviewAssignmentDAO.inc.php:453
Stack trace:
#0 /home/wnjmscom/public_html/journal/lib/pkp/classes/submission/reviewAssignment/ReviewAssignmentDAO.inc.php(139): ReviewAssignmentDAO->_fromRow(Array)
#1 /home/wnjmscom/public_html/journal/lib/pkp/classes/task/ReviewReminder.inc.php(133): ReviewAssignmentDAO->getIncompleteReviewAssignments()
#2 /home/wnjmscom/public_html/journal/lib/pkp/classes/scheduledTask/ScheduledTask.inc.php(146): ReviewReminder->executeActions()
#3 /home/wnjmscom/public_html/journal/lib/pkp/plugins/generic/acron/PKPAcronPlugin.inc.php(258): ScheduledTask->execute()
#4 [internal function]: PKPAcronPlugin->shutdownFunction()
#5 {main}
thrown in /home/wnjmscom/public_html/journal/lib/pkp/classes/submission/reviewAssignment/ReviewAssignmentDAO.inc.php on line 453

Hi @Amolowe2021,

Please do not post multiple times on the same issue. You have already posted here: Authors having issue completing submission process - #7 by Amolowe2021

This goes against our guidelines for appropriate forum behavior: Forum Guidelines and Code of Conduct

I would ask that you please be patient in expecting a response. Support on the PKP Community Forum is provided for free by PKP staff and community members. We are a small team and need to balance our time spent answering questions here on the Forum with our other work developing and maintaining our free and open source software and other services. We try our best but do not guarantee that every question will be answered or that every issue is resolved.

Please note that we may request clarifying details about your post, but may not be able to answer some or all of your questions, depending on the nature of your post/query. In some instances, questions are referred to other staff whose expertise, who may be able to assist when they are available.

You may need to seek professional support to resolve your issue. This can usually be acquired from the service provider that hosts or maintains your software, such as the technical support team at your institution or a third-party hosting provider.

-Roger
PKP Team