Ubuntu 20.04: can't install Polr

[Sanookmakmak]

PHP 7.4.3

I stuck at the step "Install composer dependencies" of http://docs.polrproject.org/en/latest/user-guide/installation/#installation

How to fix it please?

composer install --no-dev -o

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Package jeremeamia/superclosure is abandoned, you should avoid using it. Use opis/closure instead.
Package mtdowling/cron-expression is abandoned, you should avoid using it. Use dragonmantank/cron-expression instead.
Package phpoffice/phpexcel is abandoned, you should avoid using it. Use phpoffice/phpspreadsheet instead.
Package fzaninotto/faker is abandoned, you should avoid using it. No replacement was suggested.
Package phpunit/php-token-stream is abandoned, you should avoid using it. No replacement was suggested.
Package phpunit/phpunit-mock-objects is abandoned, you should avoid using it. No replacement was suggested.
Generating optimized autoload files
Class PHPExcel_Polynomial_Best_Fit located in ./vendor/phpoffice/phpexcel/Classes/PHPExcel/Shared/trend/polynomialBestFitClass.php does not comply with psr-0 autoloading standard. Skipping.
Class PHPExcel_Power_Best_Fit located in ./vendor/phpoffice/phpexcel/Classes/PHPExcel/Shared/trend/powerBestFitClass.php does not comply with psr-0 autoloading standard. Skipping.
Class PHPExcel_Exponential_Best_Fit located in ./vendor/phpoffice/phpexcel/Classes/PHPExcel/Shared/trend/exponentialBestFitClass.php does not comply with psr-0 autoloading standard. Skipping.
Class PHPExcel_Logarithmic_Best_Fit located in ./vendor/phpoffice/phpexcel/Classes/PHPExcel/Shared/trend/logarithmicBestFitClass.php does not comply with psr-0 autoloading standard. Skipping.
Class PHPExcel_Best_Fit located in ./vendor/phpoffice/phpexcel/Classes/PHPExcel/Shared/trend/bestFitClass.php does not comply with psr-0 autoloading standard. Skipping.
Class PHPExcel_Linear_Best_Fit located in ./vendor/phpoffice/phpexcel/Classes/PHPExcel/Shared/trend/linearBestFitClass.php does not comply with psr-0 autoloading standard. Skipping.
Carbon 1 is deprecated, see how to migrate to Carbon 2.
https://carbon.nesbot.com/docs/#api-carbon-2
    You can run './vendor/bin/upgrade-carbon' to get help in updating carbon and other frameworks and libraries that depend on it.
10 packages you are using are looking for funding.
Use the `composer fund` command to find out more!

./vendor/bin/upgrade-carbon

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

  Problem 1
    - composer/composer[2.3.0, ..., 2.3.5] require symfony/console ^5.4.1 || ^6.0 -> found symfony/console[v5.4.1, ..., v5.4.9, v6.0.0, ..., v6.1.1] but the package is fixed to v2.7.51 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command.
    - composer/composer[2.3.6, ..., 2.3.7] require symfony/console ^5.4.7 || ^6.0.7 -> found symfony/console[v5.4.7, v5.4.8, v5.4.9, v6.0.7, ..., v6.1.1] but the package is fixed to v2.7.51 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command.
    - Root composer.json requires composer/composer ^2.3 -> satisfiable by composer/composer[2.3.0, ..., 2.3.7].

Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.
You can also try re-running composer require with an explicit version constraint, e.g. "composer require composer/composer:*" to figure out if any version is installable, or "composer require composer/composer:^2.1" if you know which you need.

Installation failed, reverting ./composer.json and ./composer.lock to their original content.
PHP Fatal error:  Uncaught Error: Class 'Composer\Composer' not found in /var/www/clients/client1/web29/web/vendor/nesbot/carbon/src/Carbon/Upgrade.php:131
Stack trace:
#0 /var/www/clients/client1/web29/web/vendor/nesbot/carbon/bin/upgrade-carbon(27): Carbon\Upgrade::upgrade()
#1 /var/www/clients/client1/web29/web/vendor/bin/upgrade-carbon(115): include('/var/www/client...')
#2 {main}
  thrown in /var/www/clients/client1/web29/web/vendor/nesbot/carbon/src/Carbon/Upgrade.php on line 131

[cidrbl0ck]

Wanted to comment as I'm now worried a bit by this. @Sanookmakmak Did you ever resolve this?

[cidrbl0ck]

Yup encountered identical problem on fresh install on Ubu 20.04.