Election watchdogs have vowed that the chaos which left hundreds of people unable to vote will "never happen again".
The Electoral Commission is carrying out an inquest into what happened - which has been roundly condemned by the leaders of the main parties - and has called on people affected to contact them.
High turnouts caused problems at polling stations in places like London, Sheffield, Manchester, Liverpool and Newcastle, with some polling stations running out of ballot papers and others locking furious people outside.
There were angry scenes in Hackney, east London, where would-be voters staged a sit-in after they were told they could not vote, and in Nick Clegg's constituency of Sheffield Hallam, students tried to prevent ballot boxes being taken to the count after they were turned away.
Jenny Watson, Chair of the Electoral Commission (EC), said: "Casting a vote on election day is one of the most important things we do in a democracy, and people will rightly be upset and angry if they were unable to do this. Whilst millions cast their vote without difficulties, we share the concern of all those that missed out."
"We will obviously be talking to Returning Officers. But we want to hear from voters who experienced problems on polling day - whether they were unable to cast their votes, or encountered any other difficulties. This will help us identify what went wrong and what needs to change so it never happens again."
Human rights campaign group Liberty said it was also looking into allegations that hundreds of potential voters were disenfranchised. People who were prevented from voting were urged to contact Liberty "with a view to further action".