Error guzzlehttp/guzzle ^6.3 -> no matching package found when update from 8.7.9 to 8.8.1 When i tried to update my project using composer from 8.7.9 to 8.8.1 i get the following error:

Command:

composer update drupal/core --with-dependencies



  [Composer\DependencyResolver\SolverProblemsException]
    Problem 1
        - Installation request for drupal/core 8.8.1 -> satisfiable by drupal/core[8.8.1].
        - drupal/core 8.8.1 requires guzzlehttp/guzzle ^6.3 -> no matching package found.
      Problem 2 .
        - drupal/core 8.8.1 requires guzzlehttp/guzzle ^6.3 -> no matching package found.
        - drupal/ultimate_cron 2.x-dev requires drupal/core ^8.5 -> satisfiable by drupal/core[8.8.1].
        - Installation request for drupal/ultimate_cron ^2.0 -> satisfiable by drupal/ultimate_cron[2.x-dev].
  
  Potential causes:
     - A typo in the package name .
     - The package is not available in a stable-enough version according to your minimum-stability setting . 
       see https://getcomposer.org/doc/04-schema.md#minimum-stability for more details.
     - It's a private package and you forgot to add a custom repository to find it


Any ideas ?
I have just to remove the vendor Folder it works now:
For the complete steps see 8.5.6 Update not being recognized .