Hi,
I tried to upgrade today using my "old" composer.json file but i faced lotsa errors.
After a long time, i decided to use the json template here https://github.com/magento/magento2/blob/2.4-develop/composer.json and could update easilly.
I just added at the end of this file the pathes pf my other extensions like in my previous json file :
"repositories": {
"0": {
"type": "composer",
"url": "https://repo.magento.com/"
},
"owebia-magento2-module-adv-ship-functions-addon": {
"type": "package",
"package": {
"name": "owebia/magento2-module-adv-ship-functions-addon",
"version": "1.0.1",
"dist": {
"url": "./packages/owebia/magento2-module-adv-ship-functions-addon.tar.gz",
"type": "tar"
},
"require": {
"php": "~5.5.0|~5.6.0|~7.0.0|~7.1.0|~7.3.0",
"magento/magento-composer-installer": "*"
},
"autoload": {
"files": [
"registration.php"
],
"psr-4": {
"Owebia\\AdvShipFunctionsAddon\\": ""
}
}
}
},
"owebia-magento2-module-adv-ship-unlimited-carriers-addon": {
"type": "package",
"package": {
"name": "owebia/magento2-module-adv-ship-unlimited-carriers-addon",
"version": "1.0.1",
"dist": {
"url": "./packages/owebia/magento2-module-adv-ship-unlimited-carriers-addon.tar.gz",
"type": "tar"
},
"require": {
"php": "~5.5.0|~5.6.0|~7.0.0|~7.1.0|~7.3.0",
"magento/magento-composer-installer": "*"
},
"autoload": {
"files": ["registration.php"],
"psr-4": {
"Owebia\\AdvShipUnlimitedCarriersAddon\\": ""
}
}
}
},
"amasty": {
"type": "composer",
"url": "https://composer.amasty.com/community"
},
"swissuplabs": {
"type": "composer",
"url": "https://ci.swissuplabs.com/api/packages.json"
}
}But when i tried to proceed cache clear, i had an error telling me that bin/magento didn't exist anymore. I looked in the bin/ folder and saw only a folder of my migration tool was remaining... nothing else.
During those last hours, i tried :
- composer (version 1.10.13) clear-cache and composer update
- rm -r vendor/* and composer install
- rm -rf var/cache var/generation var/di
- rm -rf var/cache/* var/page_cache/* var/generation/*
- find var vendor pub/static pub/media app/etc -type f -exec chmod u+w {} \; && find var vendor pub/static pub/media app/etc -type d -exec chmod u+w {} \; && chmod u+x bin/magento
- do all above with (ssh) root user
- do all above with composer 2
- rolled back to composer 1 and retryed with the new json file
- create manually a bin/magento file with git template https://github.com/magento/magento2/blob/2.4-develop/composer.json
...
My server is on plesk + Debian 8 fresh install and all my (dev) site was working well before update. I use PHP 7.3.12.
A lot of threads are talking about empty bin/ fodler issue but only advice to verify to launch bin/magento tasks in magento root folder 
I'm not a pro but i know such things an i work with M2 since 2 years.
Permissions and ownership seem correct.
If you have an idea about this issue, it'll help me
Thanks to all.