I haven’t found similar “Slim Application Error” in my production server but I have been able to reproduce a similar error in my local environment but there was no “File not found messages”.
Before this test I have tried to download all the files attached to the article and everything was OK.
You can see a recording with my test here https://youtu.be/5OVDXgtCfo0
This is the error in apache logs.
[Fri Mar 12 20:45:24.153764 2021] [php7:notice] [pid 13860] [client 127.0.0.1:53392] Slim Application Error:
Type: Error
Message: Call to a member function getId() on null
File: /home/isaac.marco/git/ojs24/lib/pkp/classes/notification/managerDelegate/PKPEditingProductionStatusNotificationManager.inc.php
Line: 102
Trace: #0 /home/isaac.marco/git/ojs24/lib/pkp/classes/notification/PKPNotificationManager.inc.php(338): PKPEditingProductionStatusNotificationManager->updateNotification(Object(Request), NULL, 1048585, 301)
#1 /home/isaac.marco/git/ojs24/lib/pkp/classes/services/PKPSubmissionFileService.inc.php(562): PKPNotificationManager->updateNotification(Object(Request), Array, NULL, 1048585, 301)
#2 /home/isaac.marco/git/ojs24/lib/pkp/classes/submission/PKPSubmissionDAO.inc.php(128): PKP\\Services\\PKPSubmissionFileService->delete(Object(SubmissionFile))
#3 /home/isaac.marco/git/ojs24/classes/submission/SubmissionDAO.inc.php(51): PKPSubmissionDAO->deleteById(301)
#4 /home/isaac.marco/git/ojs24/lib/pkp/classes/submission/PKPSubmissionDAO.inc.php(103): SubmissionDAO->deleteById(301)
#5 /home/isaac.marco/git/ojs24/lib/pkp/classes/services/PKPSubmissionService.inc.php(783): PKPSubmissionDAO->deleteObject(Object(Submission))
#6 /home/isaac.marco/git/ojs24/lib/pkp/api/v1/_submissions/PKPBackendSubmissionsHandler.inc.php(197): PKP\\Services\\PKPSubmissionService->delete(Object(Submission))
#7 [internal function]: PKPBackendSubmissionsHandler->delete(Object(Slim\\Http\\Request), Object(APIResponse), Array)
#8 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/Handlers/Strategies/RequestResponse.php(40): call_user_func(Array, Object(Slim\\Http\\Request), Object(APIResponse), Array)
#9 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/Route.php(281): Slim\\Handlers\\Strategies\\RequestResponse->__invoke(Array, Object(Slim\\Http\\Request), Object(APIResponse), Array)
#10 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(117): Slim\\Route->__invoke(Object(Slim\\Http\\Request), Object(APIResponse))
#11 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/Route.php(268): Slim\\Route->callMiddlewareStack(Object(Slim\\Http\\Request), Object(APIResponse))
#12 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/App.php(503): Slim\\Route->run(Object(Slim\\Http\\Request), Object(APIResponse))
#13 /home/isaac.marco/git/ojs24/lib/pkp/classes/security/authorization/internal/ApiAuthorizationMiddleware.inc.php(77): Slim\\App->__invoke(Object(Slim\\Http\\Request), Object(APIResponse))
#14 [internal function]: ApiAuthorizationMiddleware->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Slim\\App))
#15 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/DeferredCallable.php(57): call_user_func_array(Object(ApiAuthorizationMiddleware), Array)
#16 [internal function]: Slim\\DeferredCallable->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Slim\\App))
#17 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(70): call_user_func(Object(Slim\\DeferredCallable), Object(Slim\\Http\\Request), Object(APIResponse), Object(Slim\\App))
#18 /home/isaac.marco/git/ojs24/lib/pkp/classes/security/authorization/internal/ApiCsrfMiddleware.inc.php(46): Slim\\App->Slim\\{closure}(Object(Slim\\Http\\Request), Object(APIResponse))
#19 [internal function]: ApiCsrfMiddleware->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#20 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/DeferredCallable.php(57): call_user_func_array(Object(ApiCsrfMiddleware), Array)
#21 [internal function]: Slim\\DeferredCallable->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#22 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(70): call_user_func(Object(Slim\\DeferredCallable), Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#23 /home/isaac.marco/git/ojs24/lib/pkp/classes/security/authorization/internal/ApiTokenDecodingMiddleware.inc.php(121): Slim\\App->Slim\\{closure}(Object(Slim\\Http\\Request), Object(APIResponse))
#24 [internal function]: ApiTokenDecodingMiddleware->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#25 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/DeferredCallable.php(57): call_user_func_array(Object(ApiTokenDecodingMiddleware), Array)
#26 [internal function]: Slim\\DeferredCallable->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#27 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(70): call_user_func(Object(Slim\\DeferredCallable), Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#28 /home/isaac.marco/git/ojs24/lib/pkp/classes/handler/APIHandler.inc.php(68): Slim\\App->Slim\\{closure}(Object(Slim\\Http\\Request), Object(APIResponse))
#29 [internal function]: APIHandler->{closure}(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#30 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/DeferredCallable.php(57): call_user_func_array(Object(Closure), Array)
#31 [internal function]: Slim\\DeferredCallable->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#32 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(70): call_user_func(Object(Slim\\DeferredCallable), Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#33 /home/isaac.marco/git/ojs24/lib/pkp/classes/handler/APIHandler.inc.php(127): Slim\\App->Slim\\{closure}(Object(Slim\\Http\\Request), Object(APIResponse))
#34 [internal function]: APIHandler->{closure}(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#35 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/DeferredCallable.php(57): call_user_func_array(Object(Closure), Array)
#36 [internal function]: Slim\\DeferredCallable->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#37 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(70): call_user_func(Object(Slim\\DeferredCallable), Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#38 /home/isaac.marco/git/ojs24/lib/pkp/classes/handler/APIHandler.inc.php(132): Slim\\App->Slim\\{closure}(Object(Slim\\Http\\Request), Object(APIResponse))
#39 [internal function]: APIHandler->{closure}(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#40 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/DeferredCallable.php(57): call_user_func_array(Object(Closure), Array)
#41 [internal function]: Slim\\DeferredCallable->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#42 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(70): call_user_func(Object(Slim\\DeferredCallable), Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#43 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(117): Slim\\App->Slim\\{closure}(Object(Slim\\Http\\Request), Object(APIResponse))
#44 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/App.php(392): Slim\\App->callMiddlewareStack(Object(Slim\\Http\\Request), Object(APIResponse))
#45 /home/isaac.marco/git/ojs24/lib/pkp/classes/handler/APIHandler.inc.php(124): Slim\\App->process(Object(Slim\\Http\\Request), Object(APIResponse))
#46 [internal function]: APIHandler->{closure}(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#47 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/DeferredCallable.php(57): call_user_func_array(Object(Closure), Array)
#48 [internal function]: Slim\\DeferredCallable->__invoke(Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#49 /home/isaac.marco/git/ojs24/lib/pkp/lib/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(70): call_user_func(Object(Slim\\DeferredCallable), Object(Slim\\Http\\Request), Object(APIResponse), Object(Closure))
#50 /home/isaac.ma
I have another shot with the other article in my local environment I you want me to try something.