There is a hard technical limit of Java that prevents large MOJO files from loading (this issue is fixed in Driverless AI version 1.6.3). Generally the error is a 


that lists the Java StringBuilder class somewhere in the stacktrace. For example you might see a line like:

at java.lang.AbstractStringBuilder.hugeCapacity(

To avoid this error, upgrade to Driverless AI version 1.6.3 or greater.