This minor release addresses a few bugs discovered after deploying 4.2.0:
* The 4.2.0 release included major improvements to the sheet application. This introduced breaking changes to the "lock" system in the application. Existing spreadsheets (before 4.2.0) that were closed by a user without "unlocking" all cells first became impossible to open after the 4.2.0 changes. This has been fixed.
* Team owners can now properly upload a team avatar.
* We've improved the file upload script to better recognize markdown files.
* We've fixed a few issues resulting in an error screen:
* New users were unable to create a drive without registering first.
* Snapshots in the sheet application couldn't be loaded.
* Loading an existing drive as an unregistered user could fail.