IT problems could cause disruption for more than 100 councils at May's local elections, the BBC has learned.
Burnley Council says problems could be nationwide
Software which reads voter signatures on postal ballots is failing, while "patches" sent to fix the problem are causing some data to be lost.
One authority, Burnley Borough Council, has had to put plans in place to read thousands of signatures manually ahead of the vote on 3 May.
It is thought 120 local authorities are using the affected software.
Burnley Council said its problems will put more pressure on an already over-stretched service.
It added that there were similar problems elsewhere in the north west of England, and it suspected it was an issue on a "national scale".
May's local elections will be the first since government reforms to increase voter participation.
Under new rules, voters can apply for postal ballots up to 11 days before the poll.
The identification required is a signature alongside a date of birth.
May's elections cover 312 English local authorities.
A Department for Constitutional Affairs spokesman said: "This is not - to our knowledge - an issue for every returning officer, or indeed for many of those using this particular software provider.
"We have provided the legislation, and significant sums of money (up to £12.2m) for the implementation of postal vote identifiers.
"We have worked closely with suppliers to ensure they will have fit-for-purpose products available, and are continuing to do so.
"They have all given assurances that they will, so it is for returning officers to ensure they work closely with their supplier of choice to complete installation of the software on their local IT in good time for the election."
Russell Osborne, of software firm Northgate Information Solutions, said he was "confident" the 75 local authorities it was working with would have successful elections.
He added: "However, there is also a robust semi-automated solution in place as a contingency, which will help ensure the smooth running of the elections in May and prevent unnecessary delays.
"Any form of innovation and improvement is likely to experience its share of teething-problems and naysayers, but we believe that the progress that has already been made with postal voting can help to deliver a modernised electoral management system, which will encourage greater participation and confidence in the democratic process."
Last month Sir Alistair Graham, chairman of the Committee on Standards in Public Life, said it was inevitable that the software would not recognise all signatures.