Same thing happened in Ljubljana, Slovenia, few years back...
From eventim.hr Adria and Entertainment:

Promoters Adria Entertaimnet and Live Nation confirmed today Madonna's concert at Maksimir Stadium in Zagreb, Croatia, was canceled due to logistical reasons. The show was previously scheduled for 11 June 2012 We are very sorry that many fans will be disappointed.
All purchasers of tickets for the previously scheduled concert can refund from 19 March 2012 at retail outlets where tickets are purchased. Fans who bought their tickets online will have the amount returned on their cards.
Those who bought their tickets at the office Adrie Entertainment, regardless of payment method, refunds can only be done at the point of sale - at the Adria Entertainment.
"Unfortunately, the world of corporate business decisions are made regarding the primary benefit of the corporation. In this case we could not go under any agreement we have with local partners and take over the logistical commitments that are subsequently placed in front of us, and refer to the manner of use of the stadium . Because of this, a joint decision that without it is not logistically possible to organize a concert in a satisfactory manner, which would bring loss to all parties in the project. So we had to cancel the concert. Refund begins 3/19/2012 and will last until the last customer does not come for a refund for your ticket. We know that this decision of the cancellation may have an impact on the market, but our long-term fairness and the public trust, we are sure, will override this challenge, and this trust will not be infringed. "- said the CEO of Adria Party, Vladimir Ivankovic.