End-of-central-directory signature not found. Either this file is not

flutter upgrade --force
Downloading Darwin x64 Dart SDK from Flutter engine 1837b5be5f0f1376a1ccf383950e83a80177fb4e...
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 193 100 193 0 0 338 0 --:--:-- --:--:-- --:--:-- 342
[/Users/ek/dev/flutter/bin/cache/dart-sdk-darwin-x64.zip]
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
unzip: cannot find zipfile directory in one of /Users/ek/dev/flutter/bin/cache/dart-sdk-darwin-x64.zip or
/Users/ek/dev/flutter/bin/cache/dart-sdk-darwin-x64.zip.zip, and cannot find /Users/ek/dev/flutter/bin/cache/dart-sdk-darwin-x64.zip.ZIP, period.

It appears that the downloaded file is corrupt; please try again.
If this problem persists, please report the problem at:
https://github.com/flutter/flutter/issues/new?template=1_activation.md