Did you update from 1.6.1 to 1.9.0 using the P2 built-in update mechanism in CubeIDE? Or did you download the full installer of CubeIDE 1.9.0 from st.com?
My guess is P2 update system...
In the log there are plenty of issues related to P2 update mechanism not being able to fetch information about all repositories. The root-causes for this could be:
Maybe you have to configure proxy setting to access internet properly?
Maybe you have a firewall blocking CubeIDE from accessing internet?
Given the vast number of different exceptions in your .log-file, my assumption is that your installation is broken. My recommendation would be to download and install the full package from st.com (not relying on P2 update)...
After that start a new workspace.
Import your projects.
Try to debug. If it does not work, maybe create new debug configurations...
As soon as you run into a problem, send us the workspace log.
I was using 1.9.0 without an issue than all of a sudden the problem occured. I reinstalled it from st's website and same issue happening. It is freeezing on the loading screen and refuses to open.(I am using it on ubuntu)