I have a problem in TYPO3 v8.5.0 dev with own extensions. After creating a proper composer.json my classes are not found. Installation was done by copy into the typo3conf/ext folder as usual and activating in extension manager. Unfortunally the ext is not in TER, so this is the only way. After activating, i'm stuck with error:
Oops, an error occurred!
Class 'XXX\ExtKey...' not found
What do I miss so my classes are found again?