composer update failed

I am upgrading a project from 2020 to 2021 but whatever I try with Composer updated checked I get this error below.

Error: Command failed: composer update -n
at checkExecSyncError (child_process.js:616:11)
at execSync (child_process.js:652:15)
at global.Exec (C:\Program Files (x86)\PHPMaker 2021\node\node_modules\phpmaker\phpmaker.js:7:354409)
at global.RunComposerUpdate (C:\Program Files (x86)\PHPMaker 2021\node\node_modules\phpmaker\phpmaker.js:7:354009)I have looked and looked but cannot see why this is happening, any pointers greatly received.

You may post the complete log. There should be error message before what you posted.

Checking PHP CLI...
Running composer update -n...
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.
  Problem 1
    - Root composer.json requires php >=7.2.0 but your php version (5.6.31) does not satisfy that requirement.
  Problem 2
    - Root composer.json requires slim/php-view ^3.0.0 -> satisfiable by slim/php-view[3.0.0].
    - slim/php-view 3.0.0 requires php ^7.1 -> your php version (5.6.31) does not satisfy that requirement.
  Problem 3
    - Root composer.json requires soundasleep/html2text ^1.1.0 -> satisfiable by soundasleep/html2text[1.1.0].
    - soundasleep/html2text 1.1.0 requires php >=7.0 -> your php version (5.6.31) does not satisfy that requirement.
  Problem 4
    - Root composer.json requires dflydev/dot-access-data ^3.0.0 -> satisfiable by dflydev/dot-access-data[v3.0.0].
    - dflydev/dot-access-data v3.0.0 requires php ^7.1 || ^8.0 -> your php version (5.6.31) does not satisfy that requirement.
  Problem 5
    - Root composer.json requires selective/samesite-cookie ~0.2.2 -> satisfiable by selective/samesite-cookie[0.2.2].
    - selective/samesite-cookie 0.2.2 requires php ^7.2 || ^8.0 -> your php version (5.6.31) does not satisfy that requirement.
  Problem 6
    - slim/slim[4.5.0, ..., 4.6.0] require php ^7.2 -> your php version (5.6.31) does not satisfy that requirement.
    - slim/slim[4.7.0, ..., 4.7.1] require php ^7.2 || ^8.0 -> your php version (5.6.31) does not satisfy that requirement.
    - Root composer.json requires slim/slim ^4.5.0 -> satisfiable by slim/slim[4.5.0, 4.6.0, 4.7.0, 4.7.1].

ccplusit wrote:

Root composer.json requires php >=7.2.0 but your php version (5.6.31) does not satisfy that requirement.

As the error message said. Note that v2021 requires PHP >= 7.2, see System Requirements.

Finally got Composer to generate thanks, I had to change settings on my PC system to find php7.2

I have the same problem, but the error its little different

Checking PHP CLI...
Running composer update -n...
  [Composer\Exception\NoSslException]
  The openssl extension is required for SSL/TLS protection but is not available. If you can not enable the openssl extension, you can disable this error, at your own risk, by setting the 'disable-tls' option to true.
...

Can someone help me?My phpmaker version: v2021.0.15
Php version: 7.4.19
Composer version: 2.1.3

As the error said:

The openssl extension is required for SSL/TLS protection but is not available

You need to enable openssl extension. Read:
https://phpmaker.dev/docs/#/composer.html