diff --git a/sentry-android-core/src/test/java/io/sentry/android/core/InternalSentrySdkTest.kt b/sentry-android-core/src/test/java/io/sentry/android/core/InternalSentrySdkTest.kt
index 6fbc7b1ebe..e4449f7154 100644
--- a/sentry-android-core/src/test/java/io/sentry/android/core/InternalSentrySdkTest.kt
+++ b/sentry-android-core/src/test/java/io/sentry/android/core/InternalSentrySdkTest.kt
@@ -9,6 +9,7 @@ import com.google.common.truth.Truth.assertThat
 import io.sentry.Breadcrumb
 import io.sentry.Hint
 import io.sentry.IScope
+import io.sentry.ISentryExecutorService
 import io.sentry.Scope
 import io.sentry.ScopeType
 import io.sentry.Sentry
@@ -30,6 +31,7 @@ import io.sentry.protocol.Contexts
 import io.sentry.protocol.Mechanism
 import io.sentry.protocol.SentryId
 import io.sentry.protocol.User
+import io.sentry.test.ImmediateExecutorService
 import io.sentry.test.createTestScopes
 import io.sentry.transport.ITransport
 import io.sentry.transport.RateLimiter
@@ -38,7 +40,6 @@ import java.io.ByteArrayOutputStream
 import java.io.InputStreamReader
 import java.util.concurrent.atomic.AtomicReference
 import kotlin.test.BeforeTest
-import kotlin.test.Ignore
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertNotEquals
@@ -58,10 +59,12 @@ class InternalSentrySdkTest {
     val capturedEnvelopes = mutableListOf<SentryEnvelope>()
     lateinit var options: SentryOptions
 
-    fun init(context: Context) {
+    fun init(context: Context, executorService: ISentryExecutorService? = null) {
       initForTest(context) { options ->
         this@Fixture.options = options
         options.dsn = "https://key@host/proj"
+        // Session persistence tests can finish startup rotation before writing session.json.
+        executorService?.let { options.executorService = it }
         options.setTransportFactory { _, _ ->
           object : ITransport {
             override fun close(isRestarting: Boolean) {
@@ -484,7 +487,7 @@ class InternalSentrySdkTest {
   @Test
   fun `captureEnvelopeNonTerminating keeps the session Ok and flags the unhandled error`() {
     val fixture = Fixture()
-    fixture.init(context)
+    fixture.init(context, executorService = ImmediateExecutorService())
 
     val originalSid = AtomicReference<String>()
     Sentry.configureScope { scope -> originalSid.set(scope.session!!.sessionId) }
@@ -613,18 +616,10 @@ class InternalSentrySdkTest {
     assertThat(activeSession.get().sessionId).isNotEqualTo(oldSid)
   }
 
-  // Flaky: intermittently fails with FileNotFoundException reading session.json at the
-  // `sessionFile.reader()` call below, i.e. persistCurrentSession() did not leave a session file
-  // on disk by the time this test reads it back. Seen across unrelated PRs, e.g.:
-  // https://scans.gradle.com/s/55fnn6xhtfyfq/tests/task/:sentry-android-core:testReleaseUnitTest/details/io.sentry.android.core.InternalSentrySdkTest/updateSessionForDroppedEventNonTerminating%20flags%20an%20unhandled%20error%20without%20sending%20an%20envelope?top-execution=1
-  // https://scans.gradle.com/s/ojzzz4yxag7rw/tests/task/:sentry-android-core:testReleaseUnitTest/details/io.sentry.android.core.InternalSentrySdkTest/updateSessionForDroppedEventNonTerminating%20flags%20an%20unhandled%20error%20without%20sending%20an%20envelope?top-execution=1
-  // Disabling until root-caused; see https://github.com/getsentry/sentry-java/pull/5990 for the
-  // code under test.
-  @Ignore("Flaky: intermittently fails to find the persisted session.json, needs root-causing")
   @Test
   fun `updateSessionForDroppedEventNonTerminating flags an unhandled error without sending an envelope`() {
     val fixture = Fixture()
-    fixture.init(context)
+    fixture.init(context, executorService = ImmediateExecutorService())
 
     val originalSid = AtomicReference<String>()
     Sentry.configureScope { scope -> originalSid.set(scope.session!!.sessionId) }
@@ -653,7 +648,7 @@ class InternalSentrySdkTest {
   @Test
   fun `updateSessionForDroppedEventNonTerminating increments errors for a handled error without sending an envelope`() {
     val fixture = Fixture()
-    fixture.init(context)
+    fixture.init(context, executorService = ImmediateExecutorService())
 
     val originalSid = AtomicReference<String>()
     Sentry.configureScope { scope -> originalSid.set(scope.session!!.sessionId) }