UnsupportedFormatException in Linux Mint Build

Getting Started
1

When I run my little program in the IDE debugger, everything runs smoothly. So, I thought it was time to try building this version under Linux (Mint). Just to test it. Linux runs in a Oracle VM VirtualBox.

But the build gives me a ‘UnsupportedFormatException’ and I can’t figure out why. It occurs in the following part of code:
Var fP As New FolderItem(myAppPath + "SomeFileName.ext")
I checked multiple times but the path and file do exist. In the debugger it works without errors and as expected.

I can’t check the build under Windows (yet) as I’m still using the free version. I’m running the latest 2024r1.1 release.

2

Where is located the project ?
Did you have write permissions there ?

Is there’s a folder separator at the end of myAppPath ?
(I suspect this one).

3

The build prog is in: ‘Builds - ProgName/Linux 64 bit/ProgName’.

Yes, there is a separator at the end of the FilePath. Otherwise, it would also give an error in the IDE debugger. I use this to add the separator:

#If TargetWindows Then
  Return "\"
#ElseIf TargetMacOS Then
  Return "/"
#ElseIf TargetLinux Then
  Return "/"
#Endif
4

When running in the debugger, what OS is the IDE running under? Or are you running the IDE in your VM?

5

Yes, the debugger runs in the VM. A folder is created with a name starting with ‘Debug’. The file that is checked is not in this Debug folder however. It is in a sub folder of the Xojo-project folder.

6

Usually, .Child is set to access/create files inside folders. Concatenate path at file creation ?
(second best clue for the bug)

But saving in the Program folder… [yes, otherwise…]

Try to Save As Dialog (same place, then elsewhere) instead of New FolderItem.

7

I also tried .Child but without success:

Var fP As New FolderItem(myAppPath)
If fP.Child("SomeFileName.ext").Exists Then
'Code here.

It gives the same error.

I’m not saving a file but just checking the existence of a file.

I’ll copy the build to my laptop that has Linux installed. If that runs without issues, than the VM could be the problem.

8

From where in the documentation did you find this line ?

Also, what are the error # and error message ?

UnsupportedFormatException

9

I’m not sure what you mean with the first question? But you can find it here:
https://documentation.xojo.com/api/files/folderitem.html#folderitem-constructor1
It also gives some examples.

The error number is: 0 and the message is in the description of my question: UnsupportedFormatException

10

I am sorry, I do not know what I may suggest beside using GetSaveFolderItem (for example) instead of the constructor.

11

Thanks Emile, I’ll look into that.

Meanwhile I discovered it has to do something with the subfolder. If I put the file into the app folder, the problem disappears.

To avoid issues with the ‘slash direction’ I will also use the ‘.Child’.

12

I was asking which OS the IDE was running under. I was trying to be sure that you were not running the IDE and debugging under (say) macOS, and then building for Linux.

13

Ok, I didn’t get that… No, I don’t mix OS systems.

Although I’m posting in the ‘GettingStarted’, I am not new to programming. I’m getting started with Xojo… By far not a professional, but with 20+ years of programming in VB6.

14

I now changed to the following code:

Var fP As New FolderItem(myFilePathPort)
Var fF As New FolderItem
fF = fP.Child("Portable.dat")

If fF <> Nil Then
' my code

The Linux build now gives fF = ‘Nil’. While this file ‘Portable.dat’ really exists in the subfolder.

Digging a bit further makes me discover that the problem lies in the folder definition:
In the debugger, I have to use:
app.ExecutableFile.Parent.Parent.NativePath

While in the Linux build I need:
app.ExecutableFile.Parent.NativePath
(so, just 1 ‘Parent’) And it works as expected…

Ah, I think I understand now. It has to do with the creation of the ‘DebugProjectName’ folder. The project subfolders are not copied to the ‘debug’ folder. Fully understandable.

I guess that using the constant ‘DebugBuild’ is the way to circumvent this issue?

15

What is the value of fP.exists ?

16

Depends on the situation: debugger is true but the build is false. It is caused by what I describe above: ‘parent’ or ‘parent.parent’.

I consider it solved by using an if statement that uses
DebugBuild <> true then…