I just upgraded my Android Studio from 3.7 to 4.0. After upgrading, I changed the gradle dependency to 0.7.+ as indicated in the release notes.
Now, the IDE is stuck with a background task that says it is "Refreshing" my project.
I cannot run the project or do anything as those gets queued behind this task.
Note: it did a maven central update of about 100 MB before which completed successfully.
build.gradle in your module (not the top-level
Change the following (or something similar
Android Studio will nag you about Gradle version. Let it fix it. (You might have to manually change it to 0.7.+).
Sync Project with Gradle Files then gradle will download the dependencies and it's fixed.