FileMaker GO unable to access TO's at random

[OlgerDiekstra]

Hoping someone might have an idea what's happening and how to fix this.

I'm developing an iPad app (FMGo16 on iOS 10.3.3) that accesses parts of a larger DB remotely. This app has an offline part which has a slideshow and gallery. The offline app acts as a portal to the hosted app (FMS16.0.1.184 on Win2k8R2). The offline app connects to the hosted app by invoking a FMP URL. This generally works well.

Sometimes though, when the iPad has trouble connecting to the hosted DB (sometimes when I'm updating schema, layouts or scripts), the iPad will twirl, and eventually time out. Sometimes this results in the iPad no longer being able to access TO's. Rebooting the iPad, uninstalling FMGo, and sometimes after it's been idling long enough it'll be able to read TO's again. It can login to the hosted DB fine, it just can't see some tables even though nothing has changed permission wise. There don't seem to  be  ghosting connections and forcefully disconnecting the  iPad when it is connected also has no effect.

It seems to get stuck somewhere. The error message I get is "This action cannot be performed because the required table is missing". This happens when attempting to read from an existing table that the iPad and useraccount have access to. I know for a fact (triple checked) that the user trying to login has the required access to the table.

What could be causing this?

 

[GC GYM]

In the absence of an expert replying to this (we are in a different time zone to most of them) I can only offer this;

One of my files runs on a LAN that seems to have some slow/dodgy connections and has sometimes given me <table missing> where data should be. Sometimes it recovers and continues, sometimes it drops off the FMS and has to be opened again.

Maybe this is a connection problem for the data you are getting from the remote DB?

[OlgerDiekstra]

I'm pretty sure it's got to do with the connection that triggers the issue, as it usually happens when the device sits trying to connect and eventually craps up. However, I am connected to the hosted DB (I can see the connection on the admin console) and the <table missing> thing is only visible when I'm actually connected. I'm thinking the underlying issue has to do with the Draco engine temp file and it's not updated correctly when my connection issue occurs. It then takes a while for the Draco engine to flush the tempfile after which recovers. The problem is that it's really hard to troubleshoot as there's no debugger on the iPad. I can't check the filesystem on the iPad to see whether that tempfile is there, in which case I could delete it and see if that fixes the issue.

As I was trying to determine the cause yesterday, I tapped through a few layouts (I was connected after all) and all of a sudden it came good again. The lack of visibility is frustrating. FileMaker should really develop some sort of debugger for iOS.

[OlgerDiekstra]

I haven't been able to find a definite cause, but I do appear to have found a solution. My findings do suggest it gets triggered by a slow connection.

The solution appears to be to delete the linked file FMGo creates for a hosted database. This is probably the tempfile the Draco engine creates, which appears to get corrupted. Deleting the file results in FMGo creating a fresh connection and new tempfile. All I have to do now is trap for said error, invoke a script from my portal app (using the fmp protocol) that closes and deletes the linked file to the hosted database and reopen the connection. At least that way I can let the iPad recover, without the end user having to call for support.

Once I have developed a working solution I'll come back and update this thread in case someone else finds this useful.

Edited December 30, 2017 by OlgerDiekstra