JSON, for example. Or Agile Methods in general. Or TDD specifically. Or use of an ORM.
You read up on it. You build a spike solution to show that it's more efficient.
The First No-Gate
You make The Essential Pitch. You keep it simple and direct.
A manager says "that's too Blah-Blah-Blah, we don't want to add the cost/risk/complexity." Of course, it doesn't matter what specific things are said. This is management "No #1". We just can't. There is too much "we" (that is, "I, as a non-technical manager") don't understand.
The first answer must generally be "No." No manager can agree unless it was their idea before it was your idea. If they'd already heard of this and ask you to look into it, then you might get a yes. But if it was your idea first, management must say "No".
You work some more, you refine your pitch to address the Blah-Blah-Blah issue and show that it does not actually increase cost, risk or complexity.
BTW, there's no point in trying to pre-empt the initial "No". It has to be there. You have to get specific objections, so you have to go through this "No" gate.
The Second No-Gate
You make the Address-Your-Concerns Pitch. You elaborate with lots of what-ifs and alternatives and objections and solutions. Two Powerpoint slides expand to about a dozen.
A manager says "I'm not sure that it has the cost-benefit we need to see." This is management "No #2". We just can't afford it. [Yes, this is a repeat of the cost argument, but it's different because the expected response is now different.]
The second answer must always "raise the bar" from technical issues to monetary issues.
At this point, you really can't go too far. There's essentially no cost-benefit information on any element of any technology stack in use anywhere. No one sits down and finds the most cost-effective operating system, the most cost-effective language, the most cost-effective protocols. There's no data and cost-benefit is not a core part of approval. It's tangential at best.
Further, the real answer in technology selection always boils down to skills. Does the organization have the necessary skills? Do they understand it?
You work some more, you refine your pitch to address the cost-benefit issue and show that it does not actually increase cost, may reduce risk, and have have some tangible benefits.
The Third No-Gate
You make the Cost-Benefit pitch. You try to keep it factual.
At this point, you've entered a loop. Essentially, you must be redirected to address one more concern. That concern, once addressed, won't have the monetization. Back and forth until something breaks you out of the loop.
You're stuck here because there's no compelling reason to adopt. Managers talk about cost and risk and benefits and other vaguely monetary ways to determine if the technology has or creates value. But those are reasons to say "no", not "yes." Technology rarely has a compelling monetized business case. It's just a little better or a little less risky. But that involves change and any change is inherently more risky than anything else.
Remember: the first fax machine was useless until someone else got a fax machine.
So you iterate. Pitch, refine. Pitch, refine.
At some point, you either implement your spike solution, which makes management's approval a fait accompli, or some force outside IT (business demand for a new kind of software product, external force from competitors) compels the organization to make a change.
Note that there has been no change to the technology itself. JSON was unacceptable until a customer demanded JSON-format files. Now JSON is required. The organization, however, has flipped from "No with a million reasons" to "Yes".
Agile cannot be done until a customer requires it. TDD has no ROI until someone gets their project done early because of TDD. An ORM is needless complexity until the new web framework requires it.
At this point, there are a series of steps to go from "acceptable" to "required" to "standard" to "irreplaceable legacy". Those just as puzzling as the No-Gates.
It isn't possible to finesse this and reduce the frustration. The organization must resist change until compelled to make the change. Once compelled, it must then stumble forward as though all the nay-saying never happened. And what could have been a simple technology adoption must turn into a morass of competing bad ideas.
So, we can (and should) continue to find new technology. We can (and will) make the pitch. We will be shot down.
The trick is not to take it personally. Just keep refining so that when the organization is eventually compelled to adopt, we've already got it planned out.