Printer not recognizing pg-50 cartridge

No The Printer Is A Canon Pixma MP210
The Ink Cartridges that it takes are :-
Standard :- Canon PG-37 (Black) & Canon CL-38 (Colour)
Or
Extended Use :- Canon PG-40 (Black) & Canon CL-41 (Colour)

The canon pixma mp 210 uses PG-30, CL-31, PG-40, CL-41
It will not recognized the PG-50 & CL- 51
See if you can return it and exchange it for the PG-40 & CL-41.
If not, the only other way is to transfer the ink into the other ink cartridges.
The cartridge cap can be removed by a sharp tap at the back end of the cover.
You can glue back the cover.
If there is an E 1,6 Error code, Ink has run out after you install your ink cartridges
Press and hold the stop/reset button for about 10 seconds to clear the error code.

I use refilled cartridges. Okay, the printer says ink low, but it does that all the time. I ignore it. However, yesterday it printed not a problem, today it gives me code 5. Does anyone have a real solution or should I throw the printer away?

Power down the printer completely. Unplug from wall.
Re-insert all cartridges. Then power up It takes a while for the test page to print. After that you should be good to go

no both are different
Here are the list of cartridges u can use
MP210
PG-30 Pigment Black
PG-30 Pigment Black Ink Cartridge
PG-40 BLACK
CL-31 Color FINE Ink Cartridge
CL-41 Color
MP240
PG-210 Black Cartridge
CL-211XL Color Cartridge
CL-211 Color Cartridge
PG-210 XL Black Cartridge

replaced the colour new ink cartidge

Sadly Canon cripple many of their printers so that they will not accept the high yield cartridges such as the 50 & 51. As a result your printer the MP210 will only accept the 37 or 38 cartridges which are only half filled, or the 40 and 41 which are fairly full, but don't contain as much as the 50 & 51. All I can suggest is that you could try to sell the 50 on eBay, and send a strongly worded email to Canon.

Nope! Canon played a little nasty on re-fillers and made these cartridge virtually un-fillable. Not that they can't be refilled, they can. They just won't be recognized in your machine.
They have done a couple of strange things with the software and the cartridge.

1. Software writes to the cartridge to actually marry it to the machine. This encodes id numbers on the cartridge so that another machine cannot use the cartridge.
2. They have placed a "fuse" of some type in the cartridge which is actually "blown" when the "out of ink" message is displayed. This renders the cartridge un-usuable for another cycle.

I like the Canon product. Just not these particular ones. The ones that take cartridges 30/31/40/41/50/51. I have seen too many of them come into my shop for repairs after barely 2 years of use. They are un-repairable regardless of their issues.

I suggest you look at a different Canon product, one that takes the individual ink tank cartridge PG-5 and CL-8 series. These are much better machines and the printer itself will last longer.
Just be aware that you will have an added cost in the print head which is a consumable that will need to be replaced every 3 years or so!

This printer will take either the PG-30 or PG-40 (larger size) cartridges for black ink, and either the CL-31 or CL-41 (larger size) cartridges for color ink.

See this link. The PG-40 and CL-41 are high capacity versions of the PG-30 and CL-31.