Production license is completely full. user does not have production access, but i’m trying to set him up in sandbox, when i give him access and manually assign password for him, i get the following message, does anyone know what this is: ‘Only the user can change this password, as this user has access to more than one NetSuite account.’?

https://docs.oracle.com/cloud/latest/netsuitecs_gs/NSMUR/NSMUR.pdf page 81. Important: If a message appears saying that only the user can change this password, click OK to close the message. Some users access multiple NetSuite accounts with the same email address and you might not have management over all of the accounts.

the user does not have any other NS account

Not even with a former organization?

he would have a different email with a former organization, if any

True. I'll see if I come across something.

is it at all possible the user has another login with a client or something? some other user of netsuite might have your employee set up as a customer or vendor and have granted him access through that (e.g. a client or someone he does business with outside of your work).. that came up for one of our employees before.

i’m pretty sure he does not have association with any other account