January 6, 2022
-----> Building on the Heroku-20 stack
-----> Using buildpacks:
1. heroku/php
2. https://github.com/heroku/heroku-buildpack-cli
-----> PHP app detected
-----> Bootstrapping...
-----> Installing platform packages...
! ERROR: Failed to install system packages!
!
! Your platform requirements (for runtimes and extensions) could
! not be resolved to an installable set of dependencies, or a
! platform package repository was unreachable.
!
! This usually means that you (or packages you are using) depend
! on a combination of PHP versions and/or extensions that are
! currently not available on Heroku.
!
! The following is the full output from the installation attempt:
!
! > You are using Composer 1 which is deprecated. You should upgrade to Composer 2, see https://blog.packagist.com/deprecating-composer-1-support/
! > Loading repositories with available runtimes and extensions
! > Updating dependencies
! > Your requirements could not be resolved to an installable set of packages.
! >
! > Problem 1
! > - symfony/polyfill-iconv v1.24.0 requires php >=7.1 -> satisfiable by php[7.3.24, 7.3.25, 7.3.26, 7.3.27, 7.3.28, 7.3.29, 7.3.30, 7.3.31, 7.3.32, 7.3.33, 7.4.12, 7.4.13, 7.4.14, 7.4.15, 7.4.16, 7.4.19, 7.4.20, 7.4.21, 7.4.22, 7.4.23, 7.4.24, 7.4.25, 7.4.26, 7.4.27, 8.0.0, 8.0.0RC4, 8.0.1, 8.0.10, 8.0.11, 8.0.12, 8.0.13, 8.0.14, 8.0.2, 8.0.3, 8.0.6, 8.0.7, 8.0.8, 8.0.9, 8.1.0, 8.1.1].
Symfony polyfills updated to v1.24 include a new provide section in composer.json that screws up Heroku's build process.
Manually lock polyfills to previous version. For example:
"symfony/polyfill-ctype": "~v1.23.0",
"symfony/polyfill-iconv": "~v1.23.0",
"symfony/polyfill-mbstring": "~v1.23.0",
"symfony/polyfill-uuid": "~v1.23.0"
Thanks to David Zuelke at Heroku. This is is supposed to be fixed in the coming weeks.