We are facing a similar issue for a couple of users (Out of ~500), unable to submit forms on aggregate server.
org.odk.collect.android.upload.AutoSendWorker::Feedback Form - Error: Generic Exception: Error: (404) at http://aggregate.cttsamagra.xyz:8080/submission?deviceID=imei%3A861478043984356
I am sure this URL exists so not sure why a 404 is coming.
Please guide us on how to diagnose this.
ODK Aggregate version: v2.0.0
I have some experiences that might be worked for your issue.
Note: I use Google App Engine (API) as my ODK aggregate server platform.
1.I worked with 50 enumerators, and on the 1st day almost 40 of them can't submit the forms to ODK aggregate server. On the process to fix this, I found that Google App Engine (API) give its "free users" some kind like "bandwith limitation per day", only for several questionnaires can be submitted in a day to my ODK aggregate server (in my case only around 50 to 60 questionnaires). To fix this, to overcome the limitation, I set my project with billing (if the data submission exceed per day quota, google will charge me). Monitor your quota, and if you are a "google free user" like me, it will be better to calculate how many forms can be submitted in a day, before you start your project,
2.Sometimes, even when my project has been set as a billing project, some of my enumerators still can not submit their works to odk aggregate server, especially when they're at a remote area. I found that, ODK need some level of internet connection speed, make sure your enumerator have access to it.
3.the last one, check the ODK setting on all of your enumerators devices. Do the URL change on their ODK setting as I mentioned on my previous reply.
Hope those experiences help you fix your problem.