Barnet Council has pledged to launch an investigation after a blunder with voter lists meant many were turned away from the ballot box.
Names were missing from polling lists across Barnet and residents, including the Chief Rabbi, who attempted to cast their vote were stopped.
The council apologised for the error and later offered emergency proxy votes to residents who had been affected.
The council said it will launch an investigation once the results in London have been declared.
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All of Barnet's 155 polling stations were affected and the council is still unable to say how many of the 236,196 registered voters had been turned away.
Candidates and voters can challenge the result of the elections in London by lodging a petition with the Royal Courts of Justice.
Grounds for the appeal include claiming the successful candidate was not duly elected, or the election was invalidated by corrupt or illegal practices.
Sophie Walker, the Women's Equality Party (WEP) mayoral candidate, registered a complaint with the council as well as the London Assembly.
A WEP spokeswoman said: "We are waiting for more information before we decide what our next steps are."
Voters in the area questioned how the result could be "fair" when not everyone was able to have their say at the ballot box.
Chief Rabbi Ephraim Mirvis and his wife Valerie were among those to be turned away from their polling station.
He was unable to vote later in the day as he was flying to Amsterdam for a visit to the Jewish Community Centre.
Earlier this week he said Labour had a "severe" problem with anti-Semitism and warned that it would get worse if the party's inquiry into the issue was used as a "sticking plaster" to placate voters.
A Barnet Council spokesman said: "We cannot comment any further on the impact of the issues with the electoral registration lists yesterday.
"We will begin a thorough investigation into the cause of the problems once results are declared."
