On Wednesday January 30th your project will automatically be upgraded to use the new Runtime.
To ensure as smooth an experience as possible we encourage all users to upgrade and test their projects in the new environment before the automatic upgrade is made. This will help us uncover any bugs that only occur in very specific use-cases. This is particularly relevant if you have developed workers using the Worker SDKs (C++, C#, Java, C API).
You can find the full upgrade instructions here, which details behavioural changes, known issues, and workarounds. We will continue to update these as we uncover bugs and make fixes.
Please let us know if you encounter any issues or if anything in the upgrade instructions is unclear.