SPFX Development environment trouble, has anyone seen lookups.flatmap error?

Question

I recently replaced my workstation and started to begin test the new environment, however I have not been able to successfully run: yo@microsofst/sharepoint to begin scaffolding. below is what I have set up.

Node v 10.24.1 | NPM v 6.14.12

--- 
+-- @microsoft/[email protected]
+-- @pnp/[email protected]
+-- [email protected]
`-- [email protected]
---

Running yo doctor

Running sanity checks on your system
√ No .bowerrc file in home directory
√ Global configuration file is valid
√ NODE_PATH matches the npm root
√ No .yo-rc.json file in home directory
√ Node.js version
√ npm version
√ yo version

Everything looks all right!

running yo

TypeError: lookups.flatMap is not a function
at Environment.resolver.lookup enter code here

Answer 1

Looks like you are not alone. Same question is asked here this morning. I had the same error this morning when I was setting up a new environment:

For some reason, downgrading yeoman from 4.0.0 to 3.1.1 version fixed the issue. But it looks like your package versions are identical:

+-- @microsoft/[email protected]
+-- @pnp/[email protected]
+-- [email protected]
+-- [email protected]
`-- [email protected]

Perhaps, you can also try 10.24.0 nodejs instead of 10.24.1.