Unable to deploy to Google App Engine : java.lang.IllegalArgumentException: Class file is Java 8 but max supported is Java 7

Question

Got this error while trying to setup Firebase Admin SDK

Preparing to deploy: Created staging directory at: \'C:\\Users\\Parag\\AppData\\Local\\Temp\\ap

Answer 1

It seems like this is a known issue based on their release notes for firebase-admin version 4.0.0 (November 7, 2016) and version 4.0.1 (November 8, 2016):

ISSUE: This version was compiled for Java 8 and does not support Java 7. This will be fixed in an upcoming release.

I guess we'll have to wait ;)

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UPDATE:

As per their release notes, it is now fixed in version 4.0.2 - November 15, 2016:

FIXED This update restores Java 7 compatibilty for the Admin Java SDK.

Answer 2

At this time, it appears as though the firebase-admin-sdk is intended to be used on the Google Flexible Environment instead of the Standard Environment.

https://cloud.google.com/appengine/docs/flexible/java/flexible-for-standard-users

A comparable package for the Standard Environment would be firebase-server-sdk.

https://mvnrepository.com/artifact/com.google.firebase/firebase-server-sdk

However, references to the original server sdk documentation now forward to the admin sdk documentation. So, perhaps they will release an update to the Standard Environment that supports Java 8, or an update to the admin sdk that works on Java 7.