I developed an App for MacOS and Windows, and I want to build an update.
On MacOS, no trouble, everything is working well.
With the last XOJO relase 2025r2.1, I tested my App on Windows and it crashes while starting.
The debugger shows the following error:
Your application crashed due to an access violation. The Debugger may show invalid values. Check the selected line, make corrections, and try again.
> Stack - Main Thread
> Event Loop
I have no more details. What can I do?
Try launching the debug session using the “Run Paused” option. That may let you get into the debugger before whatever is causing this issue.
Thanks, I finally found the origin of the problem : a function closed its window before returning a value, and it seems to crash the program.
If you can take a minute and create a small project that crashes like this, the Xojo team would surely appreciate it. You shouldn’t be able to crash like this using conventional Xojo code.
Unless he’s returning a property of a control that belongs to the closed window.
I tried to reproduce this issue with a new project, but closing before returning a value doesn’t seem to crash the app.
It’s probably the combination with other factors that causes the crash.
It seems my issue is not fully resolved, unfortunately…
In fact, when my App is starting, I’m detecting if there is any News to display :
dim w As new wNews
var newsFound As Boolean = w.readXml(progInit)
w.Close
return newsFound
Here is the readXml function:
self.hide()
me.progInit = progInit
Dim file As FolderItem
#if TargetMachO
file = sandBoxFolder.Child("mcnews.xml")
#elseif TargetWin32
file =SpecialFolder.Preferences.child("MacCompta").child("mcnews.xml")
#endif
if (file = nil) then
'close()
return False
else
dim url As String
dim os As String
dim systemVersion As String
#if TargetMacOS then
os = "Mac OS X"
#elseif TargetWin32 then
os = "Windows"
#endif
systemVersion = getSystemVersion()
url = "https://www.mywebsite.ch/news/checknews.php?app="+str(app.majorVersion)+"."+str(app.minorVersion)+"."+str(app.bugVersion)+"&os="+os+"&v="+systemVersion+"&licence="+str(IDForSN(serialNumber))+"&lang="+kLanguageIdentifier+"&output="
url = ReplaceAll(url," ","%20")
if (System.Network.LookupIPAddress("mywebsite.ch")<>"" and socketUpdater.get(url+"xml",file, 5) and file.length>60) then
Dim xml As new XmlDocument
Dim nodeCurrentNews As XmlNode
Dim currentNewsID As Integer
Dim forceNews As Boolean = false
if(file = nil or not file.Exists) then
dim c As new Clipboard
c.Text = url
return false
end if
try
xml.loadXml(file)
xml.PreserveWhitespace = False
nodeCurrentNews = xml.DocumentElement.FirstChild
currentNewsID = val(nodeCurrentNews.Child(0).FirstChild.Value)
forceNews = (val(nodeCurrentNews.Child(1).FirstChild.Value)=1)
Catch e As XmlException
return false
end try
if(showNews(currentNewsID, forceNews)) then
dim s As new HTTPSocket
dim sourceCode As String = DefineEncoding(replaceAll(s.Get(url+"html",90),chr(13),endOfLine), Encodings.UTF8)
Dim f As FolderItem = GetTemporaryFolderItem
HTMLInfos.LoadPage(sourceCode, f)
return true
else
'close()
return False
end if
elseif(not progInit) then
'close()
return False
else
'close()
return False
end if
end if
I finally found that the App crashed when w.Close is called. If I comment this line, everything works properly, and I don’t understand why.
I checked the wNews window and the closing event is not used.
Any idea? Thanks for your help.
A simple trick to avoid such situations is not to do too much in App.Open. Instead use a single timer call and do your initialisations there.
Thanks for your replies. I tried to use a timer in my wNews that closes the window after X seconds, it seems to work now.
Why is that code even in a window? It doesn’t appear to interact with the UI at all.
Even then, the framework should throw some kind of exception.
Sure, it’s not the best way I guess, but when a news item exists, the wNews window is shown and displays it.