Build 26300 Activation fail..

Hi WiseJay,

Since you've already reinstalled Windows multiple times, I'd stop focusing on the OS and verify the license state first. I'd recommend running the following from an elevated Command Prompt:

slmgr /dlv

slmgr /xpr

These commands will confirm the installed edition, activation channel (OEM, Retail, or Volume), and whether Windows is permanently activated or reporting a licensing error. Because you're using a Dell XPS, the original Windows license is typically embedded in the system's UEFI/BIOS. If you've accidentally installed a different edition (for example, Enterprise instead of Pro, or Pro for Workstations), the embedded digital license won't activate.

One additional check is to sign in with the Microsoft account that previously held the digital license and run the Activation Troubleshooter (Settings > System > Activation > Troubleshoot) to see if the license can be re-associated with the device after the Insider build upgrade. If you can share the output of slmgr /dlv (you can redact the partial product key), it should provide enough information to determine whether this is an edition mismatch, licensing channel issue, or activation service problem.