IndexOutOfRangeException when calling Process()

[AirPanther]

Hi Paul,

BLUF: Any idea what would cause Process() to generate IndexOutOfRangeException?

Whenever I call Process(), I get the following error. The code (reads and writes) has been working perfectly for months, then this error started a few days ago, and I can't figure out what changed to cause this. I still get a successful fsuipc connection, but the reads/writes no longer sync properly to P3D (Presumably because of the error below). 

Exception thrown: 'System.IndexOutOfRangeException' in FSUIPCClient.dll
System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at FSUIPC.FSUIPCConnection.Process(Byte ClassInstance, IEnumerable`1 GroupNames)
   at FsuipcSdk.Fsuipcx.Process() in C:\Users\airpa\fsuipcx.cs:line 285

Line 285 is below:

public bool Process ()
        {
            if (FSUIPCConnection.IsOpen)
                FSUIPCConnection.Process(); // Line 285

            return true;
        }

Any thoughts are greatly appreciated,

Robert

[Paul Henty]

Hi Robert,

It's difficult to tell from that error.

What version of the DLL are you using?

Can you make sure you have the fsuipcClient.pdb file in the folder you run your application from. This should make it so the line number from my DLL is reported in the stack trace. That would help a lot. Visual Studio usually copies the pdb file to the build folder (e.g. bin/release).

Paul

[AirPanther]

Paul,

DLL Version is 3.1.9.311. fsuipcClient.pdb isn't in the folder, and I can't find it on my system. Also tried downloading from your site (application templates), but can't seem to find it. Where can I find it?

Thanks,

Robert

[Paul Henty]

That's a very old version (about 4 years). Back then I was not shipping the pdb files in the package. The pdb files are specific to each build of the DLL so I can't generate one for an old version.

I can only really suggest updating to the latest version.  There could be a few breaking changes however, depending on what features you're using.

Also, the earliest framework supported is now .NET Framework 4.6.2. If you're using an earlier framework and don't want to upgrade your project to a new framework, let me know what version you're targeting. I might be able to suggest an alternative version of the DLL that supports the framework you're using.

Paul

[AirPanther]

Ok, I will start with an update and report back. Thanks, Paul

[AirPanther]

Good morning Paul, I'm on 3.3.8 now; Downloaded from NuGet successfully. I'm not seeing the fsuipcClient.pdb. Where should I look?

 

 

[Paul Henty]

The pdb files don't seem to be in the latest packages either. I'll have to sort that out. But at least I can attach a copy for the latest version. I'll need to know which framework version you're using though - 4, 5, 6 or 7.

Paul 

[AirPanther]

Thank you; .NET Framework is 4.8.

Just wondering... does it have anything to do with target platform, or anything similar? I'm targeting x64, but have also tried x86 and Any CPU, with similar results.

Also, since upgrading, I'm now getting a second error from Process():

Exception thrown: 'System.IndexOutOfRangeException' in fsuipcClient.dll
Exception thrown: 'System.Exception' in fsuipcClient.dll
 

Robert

[Paul Henty]

Okay - here's the file. Copy it to your application folder (along side the fsuipcClient.DLL).

When you get the stack trace it should give you the line number in my Process() method where it's failing.

Paul

fsuipcClient.pdb

[AirPanther]

Thanks Paul, here's what I get:

System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at FSUIPC.FSUIPCConnection.Process(Byte ClassInstance, IEnumerable`1 GroupNames) in C:\Dev\FsuipcClient\fsuipcClient\fsuipcClient\fsuipcConnection.cs:line 707

[Paul Henty]

That line number doesn't really help unfortunately. Can you make sure FSUIPCConnection.DLLVersion is reporting 3.3.8?

Also some of this info might help:

1. are you using any named offset groups anywhere in your application? Or are you just using the blank default group?

2. is there any multi-threading in your application? Or is everything run on the main UI thread?

Paul

[AirPanther]

Hi Paul,

FSUIPCConnection.DLLVersion returns 3.3.8.410

1) I am using a named offset group called "CustomGroup"

2) No multi-threading

Robert

 

 

[AirPanther]

I went through the code and changed all offsets to not use a group, and made sure the Process() commands do not reference a group, and still getting the same error 😞

[AirPanther]

Paul, I truly appreciate your help, but decided to roll back to an earlier build from before the problem happened. It's about 30 days old, but seems like it will be easier to re-stitch the changes, than trying to find the "needle in a haystack" issue that led to this. I changed something somewhere that caused this to break, as it's been working perfectly for quite some time, but can't figure out what the change was. I'm still curious, so I don't break it again, but for the moment, the blocker is averted. I'll keep you posed if the problem becomes revealed as I'm re-stitching the updates.

You're super responsive; I truly appreciate it!

Thanks,

Robert

[AirPanther]

Wow...I FINALLY found the needle in the haystack... mainly while typing up my findings to you, Paul

I finally figured out this was an issue caused by writing to FLOAT64 variables. In my app, in the length fields, I use length 9 to differentiate between Int64 and Float64 (both length 8). I do the same thing with length 5 for Float vs. Int32 (both length 4). When initializing the offset, I didn't realize I was passing the length 9 to your module, when instead, I should have been converting 9 to 8 and 5 to 4 before initializing the offset.

This issue has always been there... but looks like I hadn't been using any FLOAT64 variables. So offset initialization didn't even occur in my mind as a possibility. I ironically, the reads work fine, especially since battery voltage is only 2 digits.

Man... this is one of those bugs I need a strong beverage after.............

I really appreciate your help Paul. Talking through it was a big help, and made me look at things from angles I hadn't considered. Thank you!

Robert

  

[Paul Henty]

Great! Glad it's all sorted. It was baffling me for sure. I hadn't considered you were using the untyped Offset class. 

I've reproduced the error here and I've made a small change to the DLL so that it gives a much better exception than "index out of range":

FSUIPC.FSUIPCException: 'FSUIPC Error #999: FSUIPC_ERR_WRITE_OVERFLOW. Offset 66C0 is declared with length of 9 Bytes. 
The data you are trying to write is different from this. (8 bytes)'

Version 3.3.9 is now on NuGet.

Paul

[AirPanther]

That's great, I will grab the update. Thanks much Paul!

Robert