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Generated by 🚫 dangerJS against 4d6d387

It seems like you haven't deprecated but removed createMuiTheme and this is breaking.

@Guneetgstar createMuiTheme is still exported in v4.12.0, proof: https://codesandbox.io/s/kind-hamilton-duc8e?file=/src/App.js.

If you were using a private import:

import createMuiTheme from "@material-ui/core/styles/createMuiTheme";

Now, you know it was private. We cover it a bit in https://material-ui.com/guides/minimizing-bundle-size/#option-1. We don't follow semver for private APIs.

import createMuiTheme from "@material-ui/core/styles/createMuiTheme";

Yeah, thats the issue. Thanks for the link.
But if we were to follow this, how do we get to use createPalette and createTypography? Should we also abandon using them at all as both of them doesn't seem to be exported from @material-ui/core/styles module?

how do we get to use createPalette and createTypography

It's private. You can't access it.