Incompatible add-on modules cause "Fatal error: Unsupported operand types in flag.module on line 1575"

This is not a bug in Flag, but instead a problem with some module that is implementing hook_flag_link_types() that is not returning an array. I'd suggest disabling any other Flag-related modules you have until the error goes away, then move this report to that module's queue. Changing "+=" to "=" will completely break Flag, as it will break all the available flag types.

Note that all other Flag-related modules are probably not yet compatible with Flag 2.x. Unless the project page specifically says it supports 2.x, it probably isn't compatible with the new version.

EDIT: I changed the module name to "Flag" instead of "Fivestar", sometimes I get a little confused cleaning up my issue queues.

Updating title to reflect problem.

Subscribing.

Following here too http://drupal.org/node/642942

Thanks for the pointer brisath. There's no point in keeping this issue open, since it's not actually caused by Flag module at all. Let's consolidate this with #642942: Flag 6.2.x-dev - is it compatible with Flag note?.