quasarframework/quasar · error

Applying the quasar.config changes failed

Error message

Applying the quasar.config changes failed

What it means

In `quasar dev`, when quasar.config.js changes the onQuasarConfChange handler re-runs the dev server with the new config via devServer.run(qConf). If that re-run rejects, the underlying error is console-logged and this warning is shown, leaving the dev server in a failed state for that config.

Source

Thrown at app-vite/lib/cmd/dev.js:110

  `../modes/${argv.mode}/${argv.mode}-devserver.js`
)
const devServer = new QuasarModeDevserver({ argv, ctx })

if (typeof quasarConf.build.beforeDev === 'function') {
  await quasarConf.build.beforeDev({ quasarConf })
}

// run possible beforeDev hooks
await ctx.appExt.runAppExtensionHook('beforeDev', async hook => {
  hook.api.logger.log(`Running beforeDev hook...`)
  await hook.fn(hook.api, { quasarConf })
})

const onQuasarConfChange = qConf => {
  log('Applying quasar.config changes...')
  devServer.run(qConf).catch(err => {
    console.error(err)
    warn('Applying the quasar.config changes failed')
  })
}

await devServer.run(quasarConf)

if (typeof quasarConf.build.afterDev === 'function') {
  await quasarConf.build.afterDev({ quasarConf })
}

// run possible afterDev hooks
await ctx.appExt.runAppExtensionHook('afterDev', async hook => {
  hook.api.logger.log(`Running afterDev hook...`)
  await hook.fn(hook.api, { quasarConf })
})

quasarConfFile.watch(onQuasarConfChange)

View on GitHub (pinned to 4841521b5f)

Solutions

1. Read the console.error(err) output printed right before this warning for the root cause
2. Fix the invalid value in quasar.config.js and save again to re-apply
3. Validate the config with `quasar prepare` or a fresh `quasar dev` restart if hot-apply keeps failing
4. Check recently added/changed options against the documented schema for your Quasar version

Example fix

// before (quasar.config.js)
framework: { plugins: ['MetaTypos'] }
// after
framework: { plugins: ['Meta'] }

// sanity-check config before saving during dev
import { quasarConfigSchema } from './schema' // or run `quasar prepare`
const valid = quasarConfigSchema.safeParse(myQuasarConfig)
if (!valid.success) console.error(valid.error)

When it happens

Trigger: Saving quasar.config.js during `quasar dev` with a config that fails to build/apply: invalid option values, unsupported plugin/framework option, bad vite config merge, or a devserver hook that throws.

Common situations: Typo in a config key (e.g. misspelled plugin name), switching boot/plugin files to a nonexistent path, invalid vite plugin added to extendViteConf, incompatible devServer options changed at runtime.

Related errors

• The queued task for "${task.diffName}" failed
• Unknown network error occurred
• Could not compile the quasar.config file because it has erro
• The quasar.config file has runtime errors. Please check the
• quasar.config file > invalid Vite plugin specified: ${name}

AI-assisted analysis of quasarframework/quasar@4841521b5f (2026-08-30). Data as JSON: /api/errors/b26b3087eaeb2ec6. Report an issue: GitHub.