If your builds fail with errors such as "fatal: reference is not a tree:..
##[error]Git checkout failed with exit code: 128",
Please do the following:
Go to the Webhooks section of the connected Bitbucket account and look for any disabled Webhooks from "mobile.azure.com"
Re-enable the Webhooks
Commit a change to the affected repository/branch and give it a try if the build runs successfully now
If your builds continue to fail, please reach out to us.