Buying currency before your trip
 

We usually buy the local currency from Wells Fargo before we begin our trip. We've never had a problem until this trip to Mexico. It turns out that Wells Fargo sold us many bills that were ancient currency, and when we unknowingly tried to spend it, we were told the establishments could not accept the money. Not a huge deal, just extremely annoying. You would expect that a huge financial organization like Wells Fargo would know better. From now on we will use in country ATMs.

Why do you usually buy foreign currency in advance of your trips?

once we stayed at an apartment that required cash for the full 3-week stay so we bought the cash from our bank instead of seeking a better rate with fellow retail travelers.

A little local paper
 

I always bring some local foreign currency in small denominations with me as I’ve had problems in the past using ATMs at certain destinations , I bring a debit card associated with a very low balance bank account I keep for this very purpose.I typically don’t use the cash except for small transactions at street merchants or tipping bell / concierge

That happened to me around 6-7 years ago with British pounds that I got from Wells Fargo prior to the trip - they gave me a bunch of currency that was being removed from circulation and no where would accept it. I ended up going to a bank in London that was willing to exchange them for stuff I could actually spend. Super frustrating and seems like a pretty basic failure. Luckily anymore I am generally cashless anywhere I go so it is no longer an issue because I rarely actually get any paper currency no matter where I'm at.

Most civilised countries central banks have details of their current banknotes on their websites, so it is worth looking there first.

I buy enough for a day or two, then depend heavily on local changers and ATMs. That way I can "hit the ground running" and not worry about getting cash right away.

When buying some UK currency from my local exchange house I pointed out a couple of old fivers which were immediately taken back.

I always arrive with local currency and if it's not available at home get a small amount immediately upon arrival at an ATM or exchange at the airport. I know it's more expensive but I've found having local cash in my pocket very helpful more than once.

Checking any country's central bank website, to verify in advance which bills, if any, are obsolete and no longer legal tender, is a very wise precaution.

By knowing, and rejecting, currency that had expired, you were able to prevent a financial loss that would likely have been unrecoverable.

issues can arise with current currency as well

while I was in Orkney last week I acquired some new £5 Scotland notes in change

since I’m going to Dublin this afternoon before returning to the US next week, I used them (along with my remaining Bank of England £5 and £10 notes) as part of a cash purchase yesterday at the Swindon location of a large (20+ UK locations) retailer … the cashier had to verify with her manager that it was ok to accept them

I hit the ATM before i go to the taxi stand. Been doing that for the past 27 years and never had a problem.

Just use an ATM at the destination. Just decline the exchange rate offered by the ATM bank. Much better rate.

Even better if you get a debit card with no or reduced FX costs. Available in most countries.

Sometimes your home bank has atrociously high commissions or fees on any international ATM withdrawal, or perhaps if it is not at an ATM that's in their preferred network (which may be a pain to go out and seek when you are in a foreign country). That, and also the possibility that ATMs you encounter may be low on cash or not working - all of it makes it a reasonable measure to get some cash in advance of your trip to get through the first few days.

There's not a chance I'm landing somewhere without some local currency in my pocket. Payment systems go down, ATMs can be empty, not all taxis take cards, bureaux de change can be closed, etc.

Like others mentioned, my family has had problems with ATMs on arrival. Our bank charges a very small fee for foreign currency. I think I paid $7.50 for $3,000 US for a mix of GBP and Euros.

I am old-school enough to travel with enough local cash for a meal and to get back to my hotel.