Update 5.3.1 > 5.4 fails


I try to update a fresh pimcore (v5.3.1 build 298 - latest git version: https://github.com/pimcore/pimcore/tree/pimcore-5.3.x) to the next possible version v5.4.0.

Both CLI and web updater generate errors:


You are going to update to build 299! Do you want to continue? (yes/no) [no]:

Downloading update 299

1/6 [====>-----------------------] 16%

Running composer update…
Deactivating maintenance mode…

[ERROR] Update was stopped by error. Please check your logs.

Erroneous job was: {“type”:“composer-invalidate-classmaps”}
Last return value was: null

Command ‘bin/console pimcore:update -u 299 -d’ is working fine and shows:
[OK] Update done!

An update of v5.3.1 build 294 to v5.4.0 also fails.
In my opinion this is caused by a missing include

‘include_once DIR . ‘/…/Pimcore.php’;’

in pimcore/lib/pimcore/Bootstrap.php