EU leaders are gathering to discuss the future direction of the bloc at a summit excluding Britain.
Underscoring the UK's new status in the departure lounge of the EU, the other 27 member states meet in Slovakia without Prime Minister Theresa May.
With Britain's withdrawal process clouded in confusion and no clear signal on whether the country intends to stay in the single market or not, Europe's leaders face a difficult task plotting a way forward.
Despite some irritation on the continent at the slow pace of Brexit, Mrs May has insisted that she will not trigger Article 50 of the Lisbon Treaty which starts the formal two year "divorce" negotiations before the end of the year at the earliest.
The Bratislava summit is intended to find consensus on a way forward for the bloc after Britain's shock vote to exit in June.
European Council president Donald Tusk said the EU must take a "brutally honest" assessment of the bloc's problems and change where needed.
"We must not let this crisis go to waste. We have to assure our citizens that we have learned the lesson from Brexit and we are able to bring back stability and a sense of security and effective protection," Mr Tusk said.
The leaders of Germany and France are keen to present a united post-Brexit vote front for the EU as both countries hold crunch national elections next year.
The refugee crisis, counter-terrorism, and tax regulation, are also set to be major issues at the summit.
Uncertainty over the pace, and scope, of Brexit was highlighted by former European Council president Herman Van Rompuy who said detailed withdrawal negotiations may not get under way until the end of 2017.
Mr Van Rompuy described the outcome of the EU referendum as a "political amputation".