How to Fix Duplicate MAC Address Problem in VMware

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Hello people,
Good Morning!

Today I came across again with a silly and easy-to-solve problem that bothers me a lot when using VMware virtual machines, which is when the following message occurs:

Ethernet0 adapter may not have network connectivity.MAC address 00: 0C: 29: 58: 61: 19 of adapter Ethernet0 is within the reserved range or is in use by another virtual adapter on your system.

Ethernet Adapter0 may not have network connectivity….

When this occurs, the virtual machine's virtual network card conflicts with the network card of other VM (s) and is likely to have internet connection issues.

The first time I saw this message, I thought that the solution to solve this situation would be to enter the VM settings> Hardware> Network Adapter> Advanced… and click on the Generate button, to generate a new MAC Address. I tried several times and this message continued to appear and the VM had no access to the network.

What causes the problem

Although not a very common mistake for most users, it is very common for those who work with multiple virtual machines, because this problem occurs when there are the following actions in sequence:
- You copy the disk file (vmdk extension) from a VM and paste it in another folder
- The two virtual machines are running simultaneously
- When the screen below appears, you have selected the option "I Moved It"

VMware Player - Duplicate MAC Address duplicated

I use this a lot because I have a VM already with a clean install of Windows with no other software installed. When I need to do some testing, I copy and paste the disk file and create a new VM to start changing, saving a lot of time with installing and configuring Windows.

How to fix and / or prevent this problem

The way to prevent this problem is very simple: just select the option “I Copied It” on the screen that appears when starting the new VM. In doing so, VMware will associate a new MAC Address for the new virtual machine, avoiding the problem reported in this post.

However, if you have already selected the “I Moved It” option, don't despair. Just turn off the VM and rename the folder where it is located.

When you open VMware again, it will inform you that this virtual machine no longer exists. You can choose to remove it from the library and add it again or just select the option “Browse for virtual machine” and choose the vmdk file again.

Once you do this, the dialog window shown above will be displayed again, where you will be asked to choose the “I Copied It” option.

And that's it!
Thanks for stopping by and see you in the next post.

VMware Player MAC Address Duplicate Duplicated Adapter Ethernet0 may not have network connectivity. MAC address 00: 0C: 29: 58: 61: 19 of adapter Ethernet0 is within the reserved address range or is in use by another virtual adapter on your system. Ethernet Adapter0 may not have network connectivity….

VMware Player MAC Address Duplicate Duplicated Adapter Ethernet0 may not have network connectivity. MAC address 00: 0C: 29: 58: 61: 19 of adapter Ethernet0 is within the reserved address range or is in use by another virtual adapter on your system. Ethernet Adapter0 may not have network connectivity….