Before You File a Bug Report Please Confirm You Have Done The Following...

• I'm using eslint-plugin-vue.
• I'm sure the problem is a parser problem. (If you are not sure, search for the issue in eslint-plugin-vue repo and open the issue in eslint-plugin-vue repo if there is no solution.
• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.

What version of ESLint are you using?

9.12.0

What version of eslint-plugin-vue and vue-eslint-parser are you using?

• [email protected]
• [email protected]

What did you do?

Use Flat Config in ESLint 9 with the default configuration.

What did you expect to happen?

No parsing error.

What actually happened?

0:0 error Parsing error: Invalid ecmaVersion
(If the espree parser is used for an SFC)

Link to Minimal Reproducible Example

The issue report is at vuejs/eslint-config-typescript#87
And a stable reproduction can be found at https://github.com/vuejs/eslint-config-typescript/tree/8954ae82336dc53fecc656bb613af1bd42c808cb/test/fixtures/with-older-espree

Additional comments

I explained the fix at my downstream config here:
https://github.com/vuejs/eslint-config-typescript/blob/aae95d60eaae711de8eccd55ee33ffd799cd188a/src/index.ts#L84-L91
But I think there's a bug in vue-eslint-parser too:

According to https://github.com/vuejs/vue-eslint-parser/blob/b0e0ccc6d302bb40c5cb496528536bd355ee5151/src/script/index.ts#L569C10-L603
The espree in the user project takes precedence over the others.
However, in

In the issue report above, as ESLint 9 now depends on espree 10.x, the latest ecmaVersion is 2025, but the project loads the espree 9.x depended by vue-eslint-parser, which doesn't recognize that version, thus the error.

By the way, if I understand correctly, as of espree 8.0.0, ecmaVersion: 'latest' is supported, so vue-eslint-parser doesn't have to normalize the version string before passing it along:
eslint/js@b068cea
The getEcmaVersionIfUseEspree can be removed entirely.