Extension manager installs incompatible extensions
Currently the extension manager installs updates which are incompatible to the current typo3 version.
Steps to reproduce:
0) Update your extension list
1) Install local (7.6) version of adodb
2) Install local (7.6) version of dbal
adodb and dbal should be installed in version 7.6.
adodb is installed in version 8.4 which is incompatible to TYPO3 7.6.