On Saturday, January 14th, the building on the MIT Campus (the Stata Center) that hosts some MIT App Inventor servers, will have its power turned off from 8AM local time until 4PM.
The critical servers that would be affected have been moved to the cloud. However some servers remaining on campus have backup power and were not moved.
The iOS buildserver was not able to be moved and will be unavailable.
If you encounter difficulties, please visit the App Inventor help section of the Community website (it is not on Campus and will remain functional).
Note: This shutdown will be repeated the next Saturday, January 21st as well.