Currently banks in Germany are refusing to exchange Ukrainian hryvnia (UAH) into EUR.
The recommendation from The National Bank of Ukraine is for people leaving Ukraine NOT to take their UAH money with them in cash. Instead, they should leave the money in their Ukrainian accounts and then use their cards abroad to either pay cashless or withdraw money into the respective national currency.
Reisebank is offering free ATM withdrawals. Please note ATM withdrawals can be very expensive from some machines.