Error: Your requirements could not be resolved to an installable set of packages.

[fozzieblue]

I followed the instructions here exactly: https://pantheon.io/docs/guides/drupal-8-composer-no-ci

When I got to the instruction to run composer update I got the following error:

➜ limitless-d8 git:(master) ✗ composer update
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

Problem 1
- drupal/core-recommended 8.8.0 requires composer/installers v1.7.0 -> satisfiable by composer/installers[v1.7.0].
- drupal/core-recommended 8.8.1 requires composer/installers v1.7.0 -> satisfiable by composer/installers[v1.7.0].
- drupal/core-recommended 8.8.2 requires composer/installers v1.7.0 -> satisfiable by composer/installers[v1.7.0].
- drupal/core-recommended 8.8.3 requires composer/installers v1.7.0 -> satisfiable by composer/installers[v1.7.0].
- drupal/core-recommended 8.8.4 requires composer/installers v1.7.0 -> satisfiable by composer/installers[v1.7.0].
- drupal/core-recommended 8.8.5 requires composer/installers v1.7.0 -> satisfiable by composer/installers[v1.7.0].
- Conclusion: don't install composer/installers v1.7.0
- Installation request for drupal/core-recommended ^8.8 -> satisfiable by drupal/core-recommended[8.8.0, 8.8.1, 8.8.2, 8.8.3, 8.8.4, 8.8.5].

I've done some sitebuilding, but I've never tried to install Drupal on Pantheon by myself before. I would be grateful for any help resolving this issue. I wasn't able to find much on a Google search.

[tostinni]

I had the same problem and resolved it by installing Drupal first by running composer update drupal/core drupal/core-dev --with-dependencies before composer update.

[fozzieblue]

@tostinni Thank you for this advice!