Recent changes to entry rules for Canadian dual passport holders has meant Canadian consulates in several countries are seeing an "unprecedented influx" of passport applications.

That influx has led to weeks-long processing delays and stress for expats.

"Travelling overseas is stressful enough, but this is making things significantly worse," said Nathan Schwarz.

Schwarz was born and raised in Kitchener, Ont. His eldest daughter Akira, 9, was also born in Kitchener and both Schwarz and his daughter are dual citizens of Canada and Australia.

"I've been keen to take the girls back to Canada for a period of time," said Schwarz.

"One daughter's actually named after a Canadian town — Elora. I wanted to show her the town she's named after, and I figured the girls are now old enough that they'd be able to remember going there. Make some good memories"

Schwarz, his two girls and his partner have tickets booked for a five-week trip to Canada on June 14. As he was arranging for electronic travel authorizations (ETAs) for the family, he learned Akira would be barred from boarding the plane unless she carried a Canadian passport as well as her Australian passport.

When Schwarz tried to apply for Akira's Canadian passport, he found "a massive backlog of applications at the consulate."

The backlog is so significant, it's prompted the High Commission in Australia to issue a special notice on its website, warning that regular passport applications for adults or children are now taking approximately 45 business days — meaning the Schwarzs wouldn't get Akira's passport until after their scheduled return from Canada.

The delays aren't isolated to the Australian consulate. Both the United Kingdom and France say they're seeing a "dramatic increase" in applications, so they are now taking twice as long as usual — as long as eight weeks to process. The delay for expats living in Germany is four to six weeks.

"It is a challenge for some families who don't have a valid Canadian passport, which is now the requirement for all Canadian citizens that are travelling back to Canada," said Chris Daw, a regulated Canadian immigration consultant of 16 years.

"But is possible to get a special authorization and that will allow people to fly."

According to Citizenship and Immigration Canada, the special authorizations are a temporary measure and were introduced at the same time as the changes to passport requirements for dual citizens.

Travellers can only apply for the special authorization no more than 10 days before their scheduled flight date, there are no guarantees they'll be granted and the authorization is only valid for four days from the indicated travel date.

And, according to an email statement from Citizenship and Immigration Canada, special authorizations can only be issued if a traveller's Canadian citizenship can be electronically verified.

Those electronic records exist if someone had:

"There are no quick fixes to help you get on your flight" if you can't get a special authorization, according to the Citizenship and Immigration Canada website, so travel may have to be rebooked.

"If travel is required urgently, a temporary passport can be issued in less than 20 days if a regular passport cannot be processed in time. The temporary passport can then be exchanged at a later time for a regular passport.

If that option isn't available, an Emergency Travel Document may be issued for a single journey to Canada," said Citizenship and Immigration Canada in an email to CBC News.

Both are only issued under "strict conditions."

The department says the special authorizations are a temporary measure. They were only supposed to be in place until January, but have since been extended as the overwhelming delays at Canadian consulates all over the world are steering travellers towards the special authorizations.

According to numbers provided by Citizenship and Immigration Canada, the department has issued more than 7,600 special authorizations since Nov. 2, 2016, when the application form went live online, putting the temporary measure in very high demand.

Between November 2016 and March 31, 2017, CIC said more than 279,000 passports had been issued at missions overseas.

The Schwarz family has decided to apply for the special authorization for Akira when the 10-day deadline rolls around on June 4, but with no guarantees she'll get it, the situation has been stressful.

Canadian dual citizens are advised to have and keep a valid Canadian passport to avoid any problems entering the country.