ESSEN, Germany — The Ruhrtriennale, an international arts festival that reanimates the disused factories of Germany’s rust belt every summer, has acquired a reputation for being ambitious, eclectic and unpredictable.

This year, maybe a little too unpredictable.

The festival’s new artistic director, Stefanie Carp, has been in trouble since June, when she rescinded an invitation to the Scottish rap band Young Fathers to perform because of the band’s support for the B.D.S. (Boycott, Divestment and Sanctions) movement. B.D.S. asks artists and businesses to avoid contact with Israel to protest its treatment of the Palestinians, but Germany’s state and federal governments reject it, and ministers have described it as anti-Semitic.

After other invited artists expressed outrage at the treatment of Young Fathers and threatened to cancel their appearances, Ms. Carp sheepishly asked the Scottish band back. Unsurprisingly, it rejected her renewed overtures.

Since then, it has been open season on Ms. Carp and the festival she has put together. (It will run through Sept. 23.)