Compile build failure


Hi folks!

I am trying to build my firmware code (through both the terminal as well as the mos tool), but get an error message about the build failing. It says “error response: 400: max size 5242880 exceeded (upload size is 27801624)

I am using an ESP8266 to upload code to, and Google Cloud to communicate with the board remotely. This wasn’t a problem in the past, but for some reason now when I try to follow this process I get this error.

Not sure if this is sufficient information to help with the problem?

Your help is greatly appreciated!



Delete the build and deps directories and rerun the build command.


Thank you for your reply!

We are not able to delete these directories as we are in need of the libraries in deps directory (it’s very important). Any other suggestion on what could be the issue?

Thank you!


The issue is clearly stated in the message max size exceeded.
Move to local build. Docker is needed for local builds.


then delete the contents of deps and re-copy your libs there. That is what I do:

rm -rf deps/*; rm -rf build; cp -r /somewhere/mylib deps/ ; mos build

or follow advice and setup a local build