Hello just a BIG WARNING.

I have confirmed this now on two machines. At home and at work. If you have 15.5 installed and are still using it. Do not install 17. Once you do 15.5 will open but you will get a segmentation fault when trying to open project files or doing anything.

The Repro steps are as followed.

Have 15.5 already installed.
Install 17.
Open 17 at least once.. at least that's what I did.
close it.
Go to 15.5 drop down a sphere and go to the pyro tab and drop a shelf explosion onto the sphere. Watch Houdini crash. After that I have not been able to open any previous files or do any work in 15.5.

I have not had issues yet with 16.5 after the install however I have only opened it to make sure my files still open.

Both machines are on windows 10.

Wild guess: try adding an environment variable TBBMALLOC_PROXY_ENABLEwith value 0then try launching Houdini 15.5 again. If that works, it may be unrelated to 17.0 and more related to Windows updates breaking the memory allocator we use on Windows, tbbmalloc.

To clarify, I can't even start 15.5 in Windows 10 without disabling tbbmalloc, because of Windows updates that lead to a crash on startup if it's enabled. There's not a lot we can do about the issue if it's that, unfortunately, other than telling people to add the environment variable. You'll probably want to remove the environment variable or set it to 1for 17.0, though, 'cause tbbmalloc is a lot faster than the default allocator.

Sorry but that did not fix it. Again 15.5 was working just fine… until the install of 17. This is easily reproduce able
TBBMALLOC_PROXY_ENABLE=0

And has been confirmed by different people on the Houdini Game Dev section on facebook.
https://www.facebook.com/groups/houdiniforgamedev/ [www.facebook.com]

Strange. Another report of a similar crash just this morning was fixed by setting the environment variable, though they were on Windows 7. If you copy the tbb.dll, tbbmalloc.dll, and tbbmalloc_proxy.dll from H17.0's bin directory and paste them in H15.5's bin directory, does that fix it?

I copied the 3 dll files from 16.5 into the 15.5 folder and that worked. Thanks

Interesting. It must not have been picking up the environment variable correctly. Good to know that it's just tbbmalloc, though. Hopefully we can find some way to try to reduce the impact of any future tbbmalloc compatibility breaks due to Windows updates, since I think it's happened a few times now.

Its strange that it only broke on 15.5
Not 15.0 or 16 or 16.5

even fresh installs did not help. But were good to go now.