On Sat, 11 Feb 2023 16:31:56 +0100, Martin Frb via lazarus <lazarus@lists.lazarus-ide.org> wrote:
>On 11/02/2023 12:23, Bo Berglund via lazarus wrote: >> >> >> Then rebuilt and tried to run, but I get an immediate fatal exception! >> This happens both when starting within Lazarus and from the exe file itself. >> Message: >> -------------------------------------------------------- >> | Project AppManager raised exception class 'External: | >> | ACCESS VIOLATION' with message: | >> | Access violation reading from address | >> | $0000000000000040 | >> | | >> | At adress 1000096AD [OK] | >> -------------------------------------------------------- >> >> How can I find the cause of this exception? >> > >Did the debugger jump to any source code? >What does the "Callstack" window show? > >If neither shows anything, the error might be in the RTL or kernel. What >does the assembler win show? > >Give the data from the error message, I guess there is a nil pointer >deref (e.g. access to a field in an object that is nil) When I wrote my last post I had problems finding a location to put a breakpoint so I could step through the code. But later I found by trial-and-error where the exception was coming from in general. And where I could put a breakpoint to start stepping from. It is from a logging component I have used on Delphi since more than 20 years. When it starts its logging it is supposed to read the application version info and write a start entry to today's log including the application version etc. When I moved some applications from Delohi on Windows to Lazarus on Linux I had to make a clone of the logging component where a lot of dependencies on external components for reading version etc was removed and instead the Lazarus/fpc handling was taken into account. Then it has worked fine on Lazarus at least on Linux. When porting the current application I changed the Class name for the logging component correspondingly and hoped it would be enough, but unfortunately it is not. I don't know where I should fix it yet and I don't have time to do it now when I am busy just porting the handler application. So for now I commented out all calls to the logger creation (where the exception happened) and its use so I can move on. Success! This has brought me to the verification that now the ported app is actually working regarding access to the MSSQL database! :-) The DB conmnection is needed in order to start up the app at all, without a database verified login it just shuts down. But it IS working with the MSSQLSERVER just fine so far. But I have another problem I will describe in a new thread... -- Bo Berglund Developer in Sweden -- _______________________________________________ lazarus mailing list lazarus@lists.lazarus-ide.org https://lists.lazarus-ide.org/listinfo/lazarus
