In 2014, under what politicians declared as pressure from the private sector and very much wanting the public to feel like government was showing 'leadership' in space issues, the 
European Space Agency told government employees to make an Ariane 6 rocket - but on a budget.

Which meant using mostly old stuff from Ariane 5. They gave it a generous 2020 launch target. 

It is 2023 and they are not even close. The price tag has already doubled. ESA, which is generally a lot more efficient than NASA in the US, got caught up in the political grift that adding new countries to the EU brings - everyone somehow wants more money back from the project than they put in, rather than just France and Germany getting the wealth.

So after 10 years and $4 billion they will end up with the rocket they were competing against in 2014. In the meantime, Europeans can enjoy this image of a rocket test stand they use...for simulations.

Eric Berger at Ars Technica calls it a PR headache, and it is, but I cannot let American Exceptionalism be ignored in this case. No cost and time overrun boondoggle compares to the James Webb Space Telescope. It was approved because NASA didn't tell Congress they only had a 50 percent joint confidence level they could built it at all, they didn't know how to build it, the technology didn't exist to build it, and maybe they really just wanted something Too Big To Fail. They got it, and Americans spent nearly 7000% in cost overruns and an extra 18 years before it launched. 

The year it finally launched I marveled that American high school seniors about to graduate had never known a time when JWST wasn't delayed.

An entire generation of smaller experiments were denied funding because JWST sucked so much financial oxygen out of the NASA budget room. It isn't like Congress was going to throw more good money after bad. It did eventually launch, it works great, and we have prettier pictures of space than Hubble provided. But 15,000 other space experiments denied funding due to its cost overruns could have produced some great science too.

 Good luck beating that, Europe.