[TYPO3-english] Upgrade to TYPO3 7 LTS: Install Tool empty

[Nicolai Schirawski]

Hi list,

I took a working installation Ver. 6.2 and made the following steps as
recommended in https://wiki.typo3.org/TYPO3_CMS_7.6.0:

- uninstalled all Extensions that have version numbers other than 6.2.0
- downloaded TYPO3 7.6.0 from TER, checked md5 and unpacked it
- changed the symbolic link typo3_src to point to folder typo3_src-7.6.0
- deleted everything inside typo3temp-Folder
- started the install tool: typo3/install

Result:
- page remains white
- php-error-log remains empty

If I change the symbolic link typo3_src back to Version 6.2.15,
everything works fine again. (at least after restoring PackageStates.php
to the point before uninstalling all non-system-Extensions)

Any suggestions?

Nicolai