OK, did some more tests and there are indeed issues with OSX10.10.3 DP and PB
Added two different crash reports from two apps.
<https://xojo.com/issue/38462>
(access beta testers only)
AppWrapper 3 crashes in both OSX10.10.3 DP and PB (but mine does crash too 
See my feedback case.
Update:
Even more weird:
When I compile my apps in OSX10.10.3 PB they do seem to work fine. Didn’t had any crashes anymore.
Now isn’t that weird?
At first I thought it is just ‘luck’. But I compiled several of my apps in OSX10.10.2 and those always crashes in OSX10.10.3 BP (but they do work fine in OSX10.10.2)
Doing the same (compiling with Xojo in OSX10.10.3 BP) and they work both on OSX10.10.2 and OSX10.10.3 BP !!
How’s that?
I remember… I think we are facing the same scenario here
[quote=172559:@Lisandro Mulena]@Sam Rowlands they probably broke something with the public beta, just like the 10.10.0 launch
I remember… I think we are facing the same scenario here[/quote]
Well, if this is the case the GM will have the same issue.
OK, this is consistent:
Compiling with Xojo 2015r1 in OSX10.10.2 -> results in apps that crashes when run in OSX10.10.3 BP - but they run fine in OSX10.10.2
Compiling with Xojo 2015r1 in OSX10.10.3 -> results in apps that work fine in OSX10.10.3 BP and OSX10.10.2
Any reason why this happens?
What I have found:
Compiling with Xojo 2015r1 in OSX10.10.2 → works fine in OSX10.10.3 Public Beta
Compiling with Xojo 2015r1 in OSX10.10.3 → works fine in OSX10.10.3 Public Beta
Some apps compiled with Xojo 2014 → results in crashes in OSX10.10.3 Public Beta, maybe this is the case of App wrapper
Cristoph, you are welcome to send me the App compiled in 10.10.2 so I can test it on my systems.
This is my next question, especially for @Christoph De Vocht - the apps that are crashing, is this immediately after building in Xojo? Or are you doing post-building processing such as codesigning?
Is the Xojo Team also investigating this or will we wait until FC or final is out? 
Compiling etc… is all normal in both cases. I codesign the apps with AppWrapper.
But I will now compile a app with 2015r1 in OSX10.10.2 and not codesign it and see if it still crashes in OSX10.10.3 PB
Hold on…
OK, I compiled the app with 2015r1 in OSX10.10.2 and not codesign it but still crashes in OSX10.10.3 PB
Quickly compiled the same project with 2015r1 in OSX10.10.3 and it works flawless.
Weird not?
[quote=172590:@Christoph De Vocht]OK, I compiled the app with 2015r1 in OSX10.10.2 and not codesign it but still crashes in OSX10.10.3 PB
Quickly compiled the same project with 2015r1 in OSX10.10.3 and it works flawless.
Weird not?[/quote]
And a little scary. Looks like I need to get the beta on a VM today!
What is all the commotion about???
If people use a beta OS, and then complain that your app crashes - it is their own fault.
When 10.10.3 is released, and your app still crashes - then it is time to look into it. You cannot change the functionality of the beta OS, so there is nothing you can do at the moment anyway???
Ok. So the question is: How do we FORCE our users to NOT use a beta OR to NOT rate an App which is failing on a Beta? 
Just joking…
[quote=172613:@Richard Summers]What is all the commotion about???
If people use a beta OS, and then complain that your app crashes - it is their own fault.[/quote]
We aren’t worried about people using a beta OS. We are worried that this update could be released, say, next week and lots of Xojo apps might fail. So investigation, now, is prudent.
hahaa… I was expecting this… Let’s face it, this post was becoming a booby trap
Has anyone tried running an app built in 2011R3 on the 10.10.3 beta? I have an older application that there’s no modern replacement for yet, and I’d like to alert my customers if there’s going to be a problem. Unfortunately I don’t have a spare Mac that I can install the 10.10.3 beta on to find out for myself…
I can’t see how you can look into it though, as it is probably a bug in the beta, which will be fixed before release??
If it isn’t - then start screaming and stock up on Valerian tablets
I’d love to live in your happy little world