[TYPO3-install] Core Updater fails with Error No write access to TYPO3 CMS core location

[Joe Jones]

Dear Forum,

I am a great fan of the new Core Updater since TYPO3 7. I have several installations running on a managed Server at Hetzner.de and the Core Updater works finde. Now I made a new Account on that Server for all TYPO3 8 instaltions with php 7.0 aso. I created the same structure as on the old account.

When I do the core update in TYPO3 8.1.2 on the new Account, following error message appearse:

Update to regular released version 8.2.0 is available!
Automatic TYPO3 CMS core update not possible: No write access to TYPO3 CMS core location
New TYPO3 CMS core should be installed in "/", but this directory is not writable!

The strukture on the Server is

public_html/typo3/ for the sources
public_html/websites/  for the Installtions 

- the managed Server ist a Linux Debian
- typo3_src is a symlink ( typo3_src -> ../../typo3/typo3_src-8.1.2/ )
- symlink has the rights lrwxrwxrwx
- the directories websites and typo3  have the following rights: drwx---r-x
- One path above document root has the rights drwx---r-x
- tar is avialable

ref. https://docs.typo3.org/typo3cms/InstallationGuide/Upgrade/InstallTheNewSource/Index.html

I compared the rights with the working account; seams equal. Does anyone has an idea where the problem is? 

Thanks and regards
Joe