If you come across the below error while running composer update during magento upgrade from 2.3 to 2.4

Problem 1
    - magento/magento2-functional-testing-framework 2.4.5 requires codeception/codeception ~2.3.4 || ~2.4.0  -> satisfiable by codeception/codeception[2.4.5, 2.3.4, 2.3.5, 2.3.6, 2.3.7, 2.3.8, 2.3.9, 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4].
    - magento/magento2-functional-testing-framework 2.4.5 requires codeception/codeception ~2.3.4 || ~2.4.0  -> satisfiable by codeception/codeception[2.4.5, 2.3.4, 2.3.5, 2.3.6, 2.3.7, 2.3.8, 2.3.9, 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4].   
           
  - codeception/phpunit-wrapper 7.7.0 requires phpunit/phpunit 7.5.* -> satisfiable by phpunit/phpunit[7.5.0, 7.5.1, 7.5.10, 7.5.11, 7.5.12, 7.5.13, 7.5.14, 7.5.15, 7.5.16, 7.5.17, 7.5.18, 7.5.19, 7.5.2, 7.5.20, 7.5.3, 7.5.4, 7.5.5, 7.5.6, 7.5.7, 7.5.8, 7.5.9] but these conflict with your requirements or minimum-stability.
    - codeception/phpunit-wrapper 7.6.1 requires phpunit/phpunit >=7.1 <7.6 -> satisfiable by phpunit/phpunit[7.1.0, 7.1.1, 7.1.2, 7.1.3, 7.1.4, 7.1.5, 7.2.0, 7.2.1, 7.2.2, 7.2.3, 7.2.4, 7.2.5, 7.2.6, 7.2.7, 7.3.0, 7.3.1, 7.3.2, 7.3.3, 7.3.4, 7.3.5, 7.4.0, 7.4.1, 7.4.2, 7.4.3, 7.4.4, 7.4.5, 7.5.0, 7.5.1, 7.5.10, 7.5.11, 7.5.12, 7.5.13, 7.5.14, 7.5.15, 7.5.16, 7.5.17, 7.5.18, 7.5.19, 7.5.2, 7.5.20, 7.5.3, 7.5.4, 7.5.5, 7.5.6, 7.5.7, 7.5.8, 7.5.9] but these conflict with your requirements or minimum-stability.

    - Installation request for magento/magento2-functional-testing-framework 2.4.5 -> satisfiable by magento/magento2-functional-testing-framework[2.4.5].

You can fix this issue by making changes to your composer.json file

Update your composer.json with the below data

"require-dev": {
        "allure-framework/allure-phpunit": "~1.2.0",
        "dealerdirect/phpcodesniffer-composer-installer": "^0.5.0",
        "friendsofphp/php-cs-fixer": "~2.16.0",
        "lusitanian/oauth": "~0.8.10",
        "magento/magento-coding-standard": "*",
        "magento/magento2-functional-testing-framework": "^3.0",
        "pdepend/pdepend": "~2.7.1",
        "phpcompatibility/php-compatibility": "^9.3",
        "phpmd/phpmd": "^2.8.0",
        "phpstan/phpstan": ">=0.12.3 <=0.12.23",
        "phpunit/phpunit": "^9",
        "sebastian/phpcpd": "~5.0.0",
        "squizlabs/php_codesniffer": "~3.5.4"
    },

Now run composer update again and this issue should be fixed.