Same problem here. First experienced it some months ago, and this inicially helped:
https://mtgarena-support.wizards.com/hc/en-us/articles/360000834323-Flush-DNS-and-Winsock-Reset logged in different machines
Was playing with no problems for a month until yesterday when the issue come back, but this time even following the steps above cant log in my account. Tryed in different pcs. Create a new account and weirdly it found no problems logging in

It has been happening very often, normally at the same time. I think their server is jamming, traffic over server capacity. But this is just what I imagine. I just wish they could say something about it instead of acting as if the error hasn't been reported by users.

I'm also getting this issue. When I reinstalled MTG Arena, I was finally able to log-in and play some games. But the next day, I'm getting the message all over again. I don't want to have to reinstall 7+ GB worth of files everyday just to play.

Was this resolved ? what is the solution? i cant find any help

Same for me. This bug has apparently persisted for years. MTG prints money. Please actually fix your **** with all these patches.

Same issue stated as opening post, not sure if it is just a database error, or a routing issue not allowing me to get the information to connect.

Now opening the MTG:A software doesn't do anything. Just black screen or "loading opening scene" message.

Network login problem. After matches, network error occurs locking up and suggesting resigning onto the client. Closing and attempting to rejoin client yields "unable to get collection - log on later" Later, when?

I see that this has happened to many others after software updates in the last 6 months, but no suggestions as how to solve.

Can't enter mtg arena.. no matter what I do it won't let me get pass this screen. Quest getting piled up

Same error whenever I try to challenge my girlfriend. I can challenge other players, I can play online matches normaly, but can challenge her.

have the error

found this error in the unity player log

Uploading Crash Report
NullReferenceException: Object reference not set to an instance of an object

Same Issue for me - multiple desktop machines, mobile devices, tried on different networks

Same for me. Losing server after a few turns or start of the game. Or it just won't load at all. Also have gotten several different errors from authentication errors, network error, and collection error.

Same here (in Germany) since this morning . Laptop and phone (wlan). Interestingly enough: if I use my phone as wifi-hotspot for my laptop I can connect (but only then). Weird.

I hate how they don't care and let this go on for several months, support is not useful at all

Same error. Unable to get collection....

Same error. Unable to get collection ...

Wizard of the Coast Support replied.

Problem yet not solved.

In the past, there was a rank bug that didn't increase. It took 3 months to fix it and didn't compensate anything. Come this time, I can't enter the game again. It's been a month and still can't fix it or don't care to fix it. I don't know. Poor support, service that doesn't care about customers at all.

Same error. Unable to get collection....

Same issue fix plzzz