The Election Commission on Friday said excessive exposure to illumination might have led to the malfunctioning of paper trail machines attached to Electronic Voting Machines in the Lok Sabha bye-elections in Uttar Pradesh’s Kairana and Bhandara-Gondiya in Maharashtra.

A preliminary fact-finding report submitted to the commission suggested that “failure of contrast sensors” and “failure of length sensor” caused the malfunctioning of voter verifiable paper audit trail machines during the May 28 polls, according to a statement released by the commission.

“The errors are mainly caused by excessive exposure to illumination in the polling station,” the statement said.

The commission has asked the manufacturers of the VVPAT machines – Electronics Corporation of India Limited and Bharat Electronics Limited – and its technical expert committee to suggest additional design improvements and suggestions on any layout changes in the polling stations to prevent excessive exposure to illumination in future, reported PTI. The manufacturers have also been asked to carry out a detailed technical analysis of the machines once they are free of the election process, the statement said.

“Factors responsible [for the malfunction] may include first-time use by polling staff, extreme heat, placement of VVPAT under direct light and mishandling during use,” an unidentified Election Commission spokesperson told PTI.

The commission said that 1,202 VVPATs were replaced out of the 10,365, which is about 11.6%, reported PTI.