"An error occured adding this account. Please try again later."
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Try turning off VPN or something like that, try writing to support. It is also possible that the error is that you have already linked your account to steam guard, check the account information. If it still doesn't work, just link your phone number and do 2FA through it. I hope my message will help someone. Thanks for reading.

I have had the same problem for a couple of days now. Both my own accounts and my childrens accounts...

Any fix? Or is it Steamserver problems?

ffff

same