I can confirm a similar error. Java 8u152. Four 'Inner's work. Five gives error: The type generates a string that requires more than 65535 bytes to encode i

I can confirm a similar error. Java 8u152. Four 'Inner's work. Five gives error: The type generates a string that requires more than 65535 bytes to encode in Utf8 format in the constant pool This is using Eclipse. So it is the Eclipse compiler which is integrated with the editor. I haven't tried Oracle's Java compiler. Because the problem is to do with the size of a class constant pool, the limit of four Inner's should be universal across Java compilers, IDEs, and Operating Systems. (Assuming the class name mangling algorithm is part of the class specification.)