Hey everyone.
I’ve been getting the titular error for 2 days now. I haven’t changed anything about my Unity account. I have the free personal version of Unity.
I have tried reinstalling the program but that hasn’t fixed my problem. Please help me out. I am on a deadline (I am a student) and I need to use Unity for my submission.
doing a little digging on my machine the issue seems to be the network interface Unity is locking onto.
I have Hyper-V and Docker installed on my machine and each time the machine restarts I get a new MAC address.
Looking at my file before I re-log in I get the following:
<MachineBindings>
<Binding Key="1" Value="#####-#####-#####-#####"/>
<Binding Key="2" Value="#####_##_######_##.D"/>
<Binding Key="4" Value="XXXXXXXXXXXXXXXXXXXXXXXXXXX="/>
<Binding Key="5" Value="f3:15:9f:56:67:53"/>
</MachineBindings>
And after logging in again with my serial number:
<MachineBindings>
<Binding Key="1" Value="#####-#####-#####-#####"/>
<Binding Key="2" Value="#####_##_######_##.D"/>
<Binding Key="4" Value="XXXXXXXXXXXXXXXXXXXXXXXXXXX="/>
<Binding Key="5" Value="f3:15:9f:ca:2f:f5"/>
</MachineBindings>
It seems the application is looking at the wrong interface to lock to the machine.
VERY annoying!
Sounds like maybe you should dig into your VM settings and fix the settings to not randomize a Mac every time. Not a Unity issue, for sure.
This ^^^
Generating a new MAC address on every restart is not something Unity, or any application, would expect to occur. Generally a new MAC address can safely be interpreted as different hardware, even though it is possible on some network adaptors to change their MAC via software.
That’s not 100% true. Many devices use random MAC addresses specifically in my type of development. Anyway I will fix the issue on my own but the point was I had to do some read digging to even find the issue. It would be nice if this was documented somewhere.
Either way Unity should probably lock onto a physical device or something more permanent like a CPU ID or one of the many other static UUID’s in a computer system today. Sure if I replace my CPU or some number of hardware devices that UUID may change but at least it would not change every time I reboot the machine.
I can, and will fix the random Mac on my machine but if anyone else is having this issue try looking at your c:\ProgramData\Unity\Unity_lic.ulf file to see what the machine is being bound to.
Do you have some examples of licensed development software that is designed to work with a computer that has random MAC changes? I think that Windows 10 had some hardware activation tied to the motherboard for upgrades from earlier licensed version of Windows. They might have used something similar to what you’re describing, but I did not take the time to test that.
A lot of devices use random MACs, true, but we are talking about software. To be honest, it should be in the documentation, but since the issue is tied to licensing, divulging such information on how they do licensing could prove to be a vulnerability in the worst case scenario. Just a early morning thought. 
Glad you figured it out. Have a good one!
In my case I just disabled WiFi and Bluetooth network adapters as I was using Ethernet because it was using wifi mac address then deleted the old license file from c:\ProgramData\Unity\Unity_lic.ulf and closed the unity. After doing that I restart the unity, clicked on activate license and it worked.
I disabled my wifi/bluetooth(I’m using ethernet) network adapters deleted the file, restarted my computer and it worked!
Thank you!