TYPO3 Core

Each time I try to install sys_action with the extension manager I get the following error:

Column 'content' cannot be null
Warning: Cannot modify header information - headers already sent by (output started at /home/typo3_src-4.0beta1/t3lib/class.t3lib_install.php:387) in /home/typo3_src-4.0beta1/typo3/mod/tools/em/index.php on line 1287

Install the extension sys_action with the EM.
Remove it and reinstall it - always the same error message.

If I do this as an update of a previous install under 3.8.1 the error is shown but sys_action is at least installed and working as expected. On a fresh install though the whole table is not created at all and thus sys_action won't be working.

Since the files of sys_action itself haven't changed from 3.8.1 to 4.0beta1 the error must be caused by something else.
(issue imported from #M2110)