Zack Polanski did not vote in the local elections, the Green Party has admitted - despite the leader telling his own candidate she had his vote.
The Greens said Mr Polanski "fell short of time" to update his address on the electoral register.
It added that the party chief had faced "heightened intrusion and safety risk" and had been the "target of antisemitic and homophobic abuse" which resulted in him not voting in person.
A spokesman for the party said two arrests had been made in relation to "abuse directed towards him".
Mr Polanski had previously told Hackney Mayor Zoe Garbett "you have my vote" in a video on May 3.
But it emerged he failed to register to vote after moving "as a lodger in rented accommodation" when plans to move elsewhere fell through.
There were added complications as a result of security concerns and the "extra process" to register to vote anonymously, a Green Party spokesman said.
The party previously told The Times how Mr Polanski may have used a postal vote in Hackney after he was seen campaigning in Wales on polling day.
This statement was a "miscommunication", the BBC was told.
The admission the Green Party leader did not vote comes after an investigation revealed he had falsely clamed to be a British Red Cross spokesman and to have worked for the Ministry of Justice.
The Liberal Democrats have also called for an investigation into Mr Polanski's professional background after reports he falsely claimed to be a member of the National Council for Hypnotherapy.
And in another twist, the Greens boss has also admitted to paying the incorrect council tax during a stint living on a houseboat in east London.
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A spokesman for the Green Party said: "He has immediately taken steps to pay any council tax he may be found to owe. Zack apologises sincerely for the unintentional mistake. For security reasons, we do not comment publicly on Zack’s address."
When asked for clarification, a spokesman told the BBC Mr Polanski had until recently been living on a houseboat "which came with its own unique practical circumstances and considerations".
In an advertisement to sell the boat, Mr Polanski's partner said it served as an "amazing home" for three years.
The Green boss told broadcasters on Thursday he paid monthly mooring fees for the boat and believed "the council taxes would be included in that".
He said: "I also take responsibility - it's up to me to make sure that I pay the tax that I owe.
"It's still not clear if I owe council tax or not. I've been in touch with the council.
"Even if it turns out I don't owe anything, I will still pay the appropriate amount, because of the principle."
The marina falls under Waltham Forest Borough Council, where Mr Polanski was registered to vote.
A Waltham Forest Council spokesman said it was assessing and taking legal advice over "complex factors unique to moorings".
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