Some of our customers are getting periodic crashes:

Error Message Object reference not set to an instance of an object


The stack trace show that the error is from HTMLEditor.

Specifically part of it is:

at System.windows.forms.unsafenativemethods.dispatchmessageW(MSG& msg)...

Here'w what they're doing (and I can't reproduce this).

They're editing some HTML and they hit the enter key, and this message comes up, but not all of the time. It's very weird.

Any incites as to why this could be happening?

Thanks
James Hancock

1. Latest build of HTMLEditor?

2. Any modifications?

3. Are you doing anything special in response to the Enter key?

4. Win 98?

Tim

1. Yes.
2. Nope, I've dropped all of the stuff that I've put in to see if it would fix it.
3. Nope, nothing is handled or done on any key press.
4. Nope, Win XP.

James,

I'd definitely like to fix any problems of this kind. The big question is where the exception is happening. If it is in managed code, it shouldn't be too hard to fix. If it is somewhere in mshtml it's much harder.

Are you able to reproduce the error within the vs.net IDE?

If you run, for example, the simple demo app in edit mode, does the problem occur?

If it's specific to your app, I'll gladly take a look if you email the code to me.

My view is that the editor needs to be very robust to be useful.

Tim

My problem is that I cannot reproduce it at all. (Design or full exe)

It's only a few beta testers (read customers) that have this happen and it isn't consistant.

Yes, they were able to make it happen in the demo app, which is what really weirded me out. and the error message seems to be out of managed code or in managed code that is calling unmanaged code.

Tim, I've sent you an email with the error message as a screen grab and a bunch more details.

Hope this helps!

Jamie

Tim,

I'm having exactly the same problem. In addition to the "reference not set to an instance of an object" exception I have also gotten a System.OutOfMemoryException in system.windows.forms.dll.

I am developing on Win2K. I have subclassed htmleditor and have made one change to it: I added a TranslateURLStringOut property. When I started getting the exception today, it occurred when I clicked on a hyperlink.

Note that when I first started using htmleditor a few weeks ago, I was not seeing this problem at all. Then I made some changes to the hosting form and started seeing it randomly when I did a mousedown in a treeview on the same form. I made more changes to the hosting form and the problem went away entirely. Today I changed the form again and the problem came back.

Unfortunately, I see no pattern as to what kind of form changes are triggering or supressing the problem. If there's anything I can do to help, please let me know -- this control is excellent and I very much appreciate your providing it to all of us.

George

George,

My problem at the moment is reproducing the error.

Can you zip up your project and send it me? Or a smaller project that shows this behaviour?

It's obviously important that we get this nailed.

Tim

Tim,

I have just sent you some debugging info and I'll try to create a simple app that reproduces the problem.

George

I've managed to reproduce the problem now - more news soon I hope.

Tim

... found an error in the interface definition for IDocHostShowUI which caused problems when ShowMessage or ShowHelp was called.

This fixes the problem I can reproduce.

Tim