It was something of a midnight horror show for the absent prime minister – who had asked for a helping hand with a mutinous House of Commons just before the EU summit dinner.
Instead, at an extraordinary news conference, the presidents of the European Council and Commission confirmed no more negotiations.
Council President Donald Tusk said: “The union stands by this agreement and intends to proceed with its ratifications. It’s is not open for renegotiation.”
This was repeated by Commission President Jean-Claude Juncker for good measure, who said: “We can issue some clarifications but there will be no renegotiations.”
Devastating for a UK prime minister desperate to get her deal through the Commons.
And whereas the PM had played down expectations of a breakthrough arriving at the summit, just hours after having 117 of her own MPs vote to show no confidence in her leadership, she might not have expected a marked hardening of the language in the summit communique.
The Spanish and Irish joined forces to delete a draft paragraph offering to work on extra reassurances for the UK that the backstop would be temporary.
But the real problem was that all this was after the PM had made her most heartfelt plea for reassurances to get this deal through the House of Commons and asked EU leaders to “hold nothing in reserve” to get it over the line.
Sky News established that while the meeting was happening, the PM floated the idea of setting not an expiry date to the backstop but a commencement date for the future relationship of 2022, in an effectively binding form.
But while the PM got sympathy, there was scepticism too from leaders who asked what exactly the UK wanted from a future trade deal to be agreed at such a time.
“There is no Plan B,” one diplomatic source said afterwards.
Even more troubling was the judgement from some that the EU side could simply not offer concessions at this stage, when the PM had simply not even tested opinion in the House of Commons.
Can Theresa May deliver a majority in the House? There is one for a deal, she said, and this is the only deal.
There were also signs that leaders recognised her power on the wane.
Speaking to Sky News, Irish leader Leo Varadkar emphasised no concessions on the backstop, but instead appeared to directly appeal over the head of the government to MPs, pointing out the Commons had the power to pull Article 50.
As leaders left for the night, “no-deal” preparations were being ramped up.
A slew of Brussels contingency documents are to be published next Wednesday to help members to prepare.
For good measure, Mr Juncker confirmed for the first time in public that Britons would be charged for visa-free travel to the EU post-Brexit.
Expectations were low for this summit, but this was the last thing the prime minister needed.
Not quite as bad as the shock of Salzburg, but a considerable setback when she needed help.
Something bound to be watched carefully by MPs, denied their say so far.