Microsoft is having some major issues with its Windows Insider Program right now, on all rings affecting many different device types. If you're a Windows 10 Mobile user, do not install build 16212 being offered to you, as this will cause your phone to enter a boot loop, requiring you to reset your phone with the Windows Device Recovery Tool.

Some PCs are also receiving bad builds, on all the Insider Rings. If you're seeing build 16212 from the rs_edge_case branch, do not install this build either. Microsoft appears to be suffering from an internal issue that is causing several development builds of Windows 10 to rollout publicly to Insiders.

#WindowsInsiders: pls do not install any builds being offered til you hear from us with a blog post. If you have installed, reset with WDRT. — Dona Sarkar (@donasarkar) 1 June 2017

We suggest you leave the Insider Program for the time being, until Microsoft fixes the issue and stops these rogue builds from rolling out to the public.