V12 cannot install ANY extensions manually

Hey guys,

I cannot get v12 to install ANY extension manually from the extension manager. I tried a couple of extensions from the TER that claim to support v12. I randomly tried Vite AssetCollector, Mask and Persionio Jobs. All of them failed to install via extension manager saying e.g. “Extension vite_asset_collector is not available”. This is on a fresh typo3 installation version 12.4.0 downloaded just today from the homepage using “Package Download The classic way”. Surely, this is not how it’s supposed to be? Is this some sort of permission issue on my end or is it truly a bug?

Also seems I’m not the only person with this issue:

Also found an issue in t3-forge: Bug #100730: Unable to upload extensions in ExtensionManager - TYPO3 Core - TYPO3 Forge