PackagesState.php not writeable

[joergRossdeutscher]

I used the One-click-installer from platform.sh to setup TYPOP3. Worked like a charm. Created a new admin user, changed the password, changed some text on the demo site. All went fine.

Went away from my computer.

Came back to my computer later. Backend was still open, login had expired, tried to re-login. Nothing happened, login prompt re-appeared again and again. Didn't work.

Closed window. Opened a new window with the BE-admin-URL. Found an error-message instead login form:

“Oops, an error occurred! We could not update the list of installed packages because the file /app/web/typo3conf/PackageStates.php is not writable.“

Since I am completely unexperienced with platform.sh I made an ugly hack (the site is only for “playing with platform.sh“. I added “chmod 777 web/typo3conf“ to the deploy hook. Pushed to git, could login again. (To my surprise typo3conf shows as “locked“ again in the installer tool, however, I do not care at the moment.)

Being admin now, I looked at the “Extensions“ area, found it completely disabled since composer mode is active. Which is fine, I think.

How can I deal with the problem in a not-so-dirty manner? Possibly TYPO3 does not need that file when in composer mode (don't know), however, being kept from login is a problem.