"The defective vote envelopes have glue on the top edge and on the side.
These come unstuck and the flap can still be easily opened and closed even after 20-25 minutes," Interior Minister Wolfgang Sobotka said.
"We are going to request that parliament approves a postponement of the election," Sobotka told reporters. Possible new dates are November 27 or December 4, he said.
The postponement is a further embarrassment for Austria, a wealthy and advanced Western democracy and EU member, and for the government of Chancellor Christian Kern.
Austria has been without a president since July 8 when Heinz Fischer stepped down. He was replaced on an interim basis by the speaker of parliament and two deputy speakers.
The last election result from May was annulled after Austria's highest court in July upheld claims of procedural irregularities made by the narrowly-defeated far-right.
That vote, a run-off after the first round in April, saw independent ecologist Alexander Van der Bellen narrowly beat Norbert Hofer of the Freedom Party (FPÖ) by just 31,000 votes.
The FPÖ has stoked concerns about recent record immigration, and should Hofer eventually win it would make Austria the first country in Europe since 1945 to elect a far-right president.
The far-right has jumped on the problems with the election as proof that Austria needs to be shaken up. "We just want our country back," Hofer said in a Facebook video.
The role of the Austrian president is largely -- but not entirely -- ceremonial, and a victory by Hofer would be a major boost to Europe's other surging populist movements.
45-year-old Hofer has sought to portray himself as the friendly and moderate face of the FPÖ, focusing not on immigration but on issues like EU trade deals and wanting more Swiss-style "direct democracy".
But he has also said Islam "has no place" in Austria and opposes gay marriage. Van der Bellen has also accused him of wanting Austria to follow Britain out of the European Union.
Pushing the election back poses legal problems, however, and the government is considering drawing up special legislation or even changing the constitution to allow it to happen.
Another question is whether to update the voter register as, since the last election, tens of thousands of voters have died, while a similar number have turned 16 and can now vote, media reports said.
Expert Thomas Hofer said that it was unclear which candidate the "highly embarrassing" postponement would help, but that further ahead the far-right could well profit.
"Trust in democratic institutions was already low, and this will do further damage," he told AFP.
"In the longer term, this will help the FPÖ, which has always argued that the system is on the blink."
Indeed, Hofer has jumped on the problems with the election as proof that
Austria needs to be shaken up. "We just want our country back," Hofer said in a Facebook video.