My Canon 2000D is not firing the YN560 iv speed light. So, I learned the hard way that this flash is not compatible with the hotshoe on my camera.
Is there any way I can use this camera and flash combination? What would be the cheapest and most useful way to upgrade my system?
The Godox XPRO-C and X1T-C wireless radio triggers are known to work with the Canon bodies that do not have an ISO compliant center pin.
Of course your Yongnuo can't be controlled by Godox triggers. Unfortunately, none of the E-TTL compatible (which seems to be the key to working with a camera without a center pin) Yongnuo triggers use the same protocol as the radio receivers in the YN560 IV.
Yongnuo manual only flashes and transmitter use the YN560/RF605/RF603 protocol.
Yongnuo E-TTL flashes (other than the Canon RT clones) use the YN622 protocol.
Yongnuo YN600EX-RT, YN600EX-RT II, and YN-E3-RT that are clones of Canon RT flashes use Canon's (reverse engineered) RT protocol.
Each protocol is like a different language.
So you have a few basic choices:
Don't use your YN560 IV in the hotshoe. Instead, use it as an Off Camera Flash. Bounce it off the ceiling or use it hand held. Use your 2000D built-in ETTL flash to trigger the S2 Optical Slave Mode on your YN560 IV.
S1 mode fires when ever it sees a flash which is a problem with ETTL preflash.
S2 mode fires on the second (Main) flash and ignores the ETTL pre-flash.
Optical triggering by the camera's built-in flash can work, but also has significant limitations and can be more frustration than it's worth.
Theoretically, this can be triggered by radio off-camera, which would be a good use. Unfortunately, it seems that this Yongnuo model only works with triggers which also won't work with your camera.
Therefore, I really think your best bet is to return it (or sell it used, if returning is not possible) and get something that does work — What speedlites can work with the Canon non-standard hotshoe found on their low-end camera models?. There are several options which aren't any more expensive than this one. (And several that are a lot more flexible.)
Or, if you happen to be planning to replace your camera body soon anyway, hold onto it and buy a higher-end model which does have the standard center pin. Canon is unlikely to remove this entirely from models aimed at professionals and serious amateurs, because there'd be a huge backlash. Instead, they're using it as a differentiator to keep that segment of the market away from the cheapest purchases. It's pretty likely that this will move up the model food chain into the middle segment, too, over the next few years, though, so.... if this is important to you, that's probably worth considering.
If you put a Godox X2T-C transmitter on the hotshoe of a T7/2000D, T100/4000D, or SL3/250D, it basically reinstates that sync contact with its own hotshoe. IOW, "sandwich" an X2T-C between the flash and the camera and you can use a YN-560IV or any single-pin cheapie flash on-camera.
Granted, since the YN-560 IV is a single-pin manual speedlight, you'll only be able to fire it; you won't have TTL or HSS, or camera menu communication with it since it doesn't perform those functions.
You don't have to get a full Godox off-camera flash setup. But a Godox TT685 II-C would work with full function on the 2000D and 4000D hotshoes that are missing the sync contact, as would any of the Godox X system transmitters.
