diff --git a/packages/browser/src/node/rpc.ts b/packages/browser/src/node/rpc.ts
index 7139d0da8..069a5227b 100644
--- a/packages/browser/src/node/rpc.ts
+++ b/packages/browser/src/node/rpc.ts
@@ -127,6 +127,11 @@ export function setupBrowserRpc(
     }
 
     wss.handleUpgrade(request, socket, head, (ws) => {
+      // the pool closed this instance, its pages can still reconnect while they close
+      if (!project.browser?.provider) {
+        ws.terminate()
+        return
+      }
       wss.emit('connection', ws, request)
 
       const { rpc, offCancel } = setupClient(project, rpcId, ws, { sessionId })
diff --git a/packages/vitest/src/node/pools/browser.ts b/packages/vitest/src/node/pools/browser.ts
index 1283c48b7..c6a5e4619 100644
--- a/packages/vitest/src/node/pools/browser.ts
+++ b/packages/vitest/src/node/pools/browser.ts
@@ -125,7 +125,7 @@ export function createBrowserPool(vitest: Vitest): BrowserPool {
       if (!worker) {
         debug?.('creating a worker for project %s', task.project.name)
         worker = new BrowserWorker(task.project, {
-          maxPages: getThreadsCount(task.project),
+          getMaxPages: getThreadsCount,
           getPageAllowance,
         })
         workers.set(task.project, worker)
@@ -335,6 +335,8 @@ class BrowserWorker {
   private busySessions = new Set<string>()
   private openingPages = 0
   private readySessions: Set<string>
+  private started = false
+  private _maxPages = 1
 
   private _traces: Traces
   private _otel: {
@@ -345,7 +347,7 @@ class BrowserWorker {
   constructor(
     public project: TestProject,
     private options: {
-      maxPages: number
+      getMaxPages: (project: TestProject) => number
       getPageAllowance: (worker: BrowserWorker) => number
     },
   ) {
@@ -353,7 +355,7 @@ class BrowserWorker {
     this._otel = this._traces.startContextSpan('vitest.browser')
     this._otel.span.setAttributes({
       'vitest.project': project.name,
-      'vitest.browser.provider': this.project.browser!.provider.name,
+      'vitest.browser.provider': project.config.browser.provider?.name,
     })
     this.readySessions = project._browserReadySessions
   }
@@ -384,23 +386,34 @@ class BrowserWorker {
   }
 
   get maxPages(): number {
-    return this.options.maxPages
+    return this._maxPages
   }
 
   async runTests(method: 'run' | 'collect', files: FileSpecification[]): Promise<void> {
-    this._promise ??= createDefer<void>()
+    const promise = (this._promise ??= createDefer<void>())
 
     if (!files.length) {
       debug?.('no tests found, finishing test run immediately')
-      this._promise.resolve()
-      return this._promise
+      promise.resolve()
+      return promise
     }
 
     this._method = method
-    this._providedContext = stringify(this.project.getProvidedContext())
-
     this._queue.push(...files)
 
+    // the provider is closed when the pool frees the slot of an idle instance,
+    // so a worker that reopens the instance starts a new one
+    await this.project._initBrowserProvider()
+    if (!this._queue.length) {
+      debug?.('the run was cancelled while the provider was starting')
+      this._promise = undefined
+      promise.resolve()
+      return promise
+    }
+    this.started = true
+    this._maxPages = this.options.getMaxPages(this.project)
+    this._providedContext = stringify(this.project.getProvidedContext())
+
     for (const sessionId of [...this.readySessions]) {
       if (!this._queue.length) {
         break
@@ -417,12 +430,12 @@ class BrowserWorker {
 
     await this.openPages()
     debug?.('all sessions are created')
-    return this._promise
+    return promise
   }
 
   // opens more pages when the budget allows it, e.g. after another instance finished
   grow(): void {
-    if (!this._promise || !this._queue.length) {
+    if (!this.started || !this._promise || !this._queue.length) {
       return
     }
     this.openPages().catch((error) => this.reject(error))
diff --git a/test/browser/specs/instance-concurrency.test.ts b/test/browser/specs/instance-concurrency.test.ts
index e90e3991e..f9baef96b 100644
--- a/test/browser/specs/instance-concurrency.test.ts
+++ b/test/browser/specs/instance-concurrency.test.ts
@@ -143,3 +143,36 @@ test.runIf(provider.name === 'playwright')(
     expect(openPages).toEqual([1, 1, 1])
   },
 )
+
+test.runIf(provider.name === 'playwright')(
+  'reruns instances that were closed to free a worker slot',
+  async () => {
+    const files: Record<string, string> = {
+      'label.ts': `export const label = 'label'`,
+    }
+    for (const name of names) {
+      files[`${name}.test.ts`] = `
+        import { expect, test } from 'vitest'
+        import { label } from './label'
+        test('reads the label in ${name}', () => {
+          expect(label).toBe('label')
+        })
+      `
+    }
+
+    const { fs, vitest } = await runInlineBrowserTests(files, {
+      watch: true,
+      maxWorkers: 1,
+      browser: { instances: createInstances() },
+      reporters: ['default'],
+    })
+
+    await vitest.waitForStdout(`Test Files  ${names.length} passed`)
+
+    vitest.resetOutput()
+    fs.editFile('label.ts', (content) => `${content}\n`)
+    await vitest.waitForStdout(`Test Files  ${names.length} passed`)
+
+    expect(vitest.stderr).toBe('')
+  },
+)