simplesamlphp_auth installation fails on Centos 8-server I am trying to install simplesamlphp_auth to Centos 8/Drupal 8 server according the instructions on:

https://www.drupal.org/docs/8/modules/apigee-developer-portal-kickstart/integrate-simplesamlphp-
authentication

When I run the given command I get the following output:

composer require drupal/simplesamlphp_auth:3.x-dev drupal/simplesamlphp_custom_attributes --prefer-dist
Do not run Composer as root/super user! See https://getcomposer.org/root for details
Using version ^1.0 for drupal/simplesamlphp_custom_attributes
./composer.json has been updated
&gt; DrupalProject\composer\ScriptHandler::checkComposerVersion
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
    - don't install drupal/simplesamlphp_auth 3.x-dev|install drupal/simplesamlphp_auth dev-3.x
    - Installation request for drupal/simplesamlphp_auth 3.x-dev -&gt; satisfiable by drupal/simplesamlphp_auth[3.x-dev].
    - Conclusion: remove simplesamlphp/simplesamlphp v1.17.7
    - Conclusion: don't install simplesamlphp/simplesamlphp v1.17.7
    - drupal/simplesamlphp_auth dev-3.x requires simplesamlphp/simplesamlphp ^1.18.2 -&gt; satisfiable by simplesamlphp/simplesamlphp[v1.18.2, v1.18.3, v1.18.4].
    - Can only install one of: simplesamlphp/simplesamlphp[v1.18.2, v1.17.7].
    - Can only install one of: simplesamlphp/simplesamlphp[v1.18.3, v1.17.7].
    - Can only install one of: simplesamlphp/simplesamlphp[v1.18.4, v1.17.7].
    - Installation request for simplesamlphp/simplesamlphp (locked at v1.17.7) -&gt; satisfiable by simplesamlphp/simplesamlphp[v1.17.7].


Installation failed, reverting ./composer.json to its original content.


So it seems, that for some reason the new enough simplesamlphp-package is not installable.

I have tried (in vain, though) to harvest the web about this problem, which should not be totally uncommon IMHO.

Any hints how to tackle the problem?

wbr

Hank
Sorry for the trouble. The problem was caused because I had somewhere in the past installed those modules to this (test) site of my own and forgotten it totally. After removing the old simplesamlphp_auth things seemed to go OK.