This can't be a good sign. https://themarketherald.com.au/breaking-asx-freezes-trade-to-probe-market-issues-2020-11-16
I read a HotCopper poster saying it was a botched system upgrade and lack of knowledge of how to roll back. But yes there may be a dump tomorrow for people thinking there was a security breach or something
Yes, it does seem likely to have been a botched upgrade from the weekend. Hopefully they are able to patch the bug or execute a rollback before the opening tomorrow.