TYPO3 Core

first guess: that's probably related to the missing uid handling from https://review.typo3.org/#/c/51929/ / https://review.typo3.org/#/c/52174/ ... this needs further thoughts. i can dig into that before 8.7.1 release.

This issue was also reported in the flux bugtracker on github as flux (like many other extensions) uses flexform sections.

For reference: https://github.com/FluidTYPO3/flux/issues/1400

Still present in 8.7.1

I have a content element with flexform section and it always gives a 503 error when I try to add a new section element before saving the content itself. I think it's related to this.

The exception thrown is:
#1476107295: PHP Warning: Invalid argument supplied for foreach() {mybasedir}/typo3_src/typo3/sysext/backend/Classes/Form/Container/FlexFormElementContainer.php line 48 (More information)

I'm using and admin account on TYPO3 8.7.1
The same flexform works fine on 7.6.18

Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/53215

I tried out the patch set 2 and it solves the problem for me. Thanks.

Patch set 1 for branch TYPO3_8-7 of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/53257

Was this solved on 8.7.2?
THe problem I reported on my comment still exists. Not sure if it's another problem or this issue didn't came to 8.7.2;

Hey Riccardo. What you describe looks like a different issue. The one tackled with the patch was only about flex form sections and - yes - this is now solved in TYPO2 8.7.2 thanks to Christian!

Thanks for your answer Daniel. I created an issue to the problem I've reported: #81684