diff --git a/app/src/main/java/com/nextcloud/talk/upload/chunked/ChunkedFileUploader.kt b/app/src/main/java/com/nextcloud/talk/upload/chunked/ChunkedFileUploader.kt
index e0a5ba56dec..5975e9bca1e 100644
--- a/app/src/main/java/com/nextcloud/talk/upload/chunked/ChunkedFileUploader.kt
+++ b/app/src/main/java/com/nextcloud/talk/upload/chunked/ChunkedFileUploader.kt
@@ -335,13 +335,21 @@ class ChunkedFileUploader(
         }
     }
 
+    /**
+     * Called from the worker's onStopped, which WorkManager runs inside a coroutine cancellation handler:
+     * anything thrown here crashes the process, so this function must never throw.
+     */
+    @Suppress("Detekt.TooGenericExceptionCaught")
     fun abortUpload(onSuccess: () -> Unit) {
         isUploadAborted = true
+        val client = okHttpClientNoRedirects
+        val folderUrl = uploadFolderUri.toHttpUrlOrNull()
+        if (client == null || folderUrl == null) {
+            Log.i(TAG, "Nothing to abort, chunk upload was not started")
+            return
+        }
         try {
-            DavResource(
-                okHttpClientNoRedirects!!,
-                uploadFolderUri.toHttpUrlOrNull()!!
-            ).delete { response: Response ->
+            DavResource(client, folderUrl).delete { response: Response ->
                 when {
                     response.isSuccessful -> onSuccess()
                     else -> isUploadAborted = false
@@ -349,7 +357,13 @@ class ChunkedFileUploader(
             }
         } catch (e: NotFoundException) {
             Log.i(TAG, "Chunk upload folder could not be found", e)
-            onSuccess()
+            try {
+                onSuccess()
+            } catch (callbackError: Exception) {
+                Log.w(TAG, "Abort callback failed", callbackError)
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "Failed to remove chunk upload folder", e)
         }
     }
 
diff --git a/app/src/test/java/com/nextcloud/talk/upload/chunked/ChunkedFileUploaderAbortTest.kt b/app/src/test/java/com/nextcloud/talk/upload/chunked/ChunkedFileUploaderAbortTest.kt
new file mode 100644
index 00000000000..6bfbbd747e9
--- /dev/null
+++ b/app/src/test/java/com/nextcloud/talk/upload/chunked/ChunkedFileUploaderAbortTest.kt
@@ -0,0 +1,156 @@
+/*
+ * Nextcloud Talk - Android Client
+ *
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package com.nextcloud.talk.upload.chunked
+
+import android.app.Application
+import com.nextcloud.talk.api.NcApiCoroutines
+import com.nextcloud.talk.data.user.model.User
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.mockwebserver.MockResponse
+import okhttp3.mockwebserver.MockWebServer
+import okhttp3.mockwebserver.SocketPolicy
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+import org.junit.runner.RunWith
+import org.mockito.kotlin.mock
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+import java.util.concurrent.TimeUnit
+
+/**
+ * WorkManager calls the worker's onStopped from a coroutine cancellation handler. An exception thrown by
+ * [ChunkedFileUploader.abortUpload] there crashes the process, so it must never throw, whatever the network does.
+ */
+@RunWith(RobolectricTestRunner::class)
+@Config(application = Application::class, sdk = [33])
+class ChunkedFileUploaderAbortTest {
+
+    @get:Rule
+    val tempFolder = TemporaryFolder()
+
+    private val server = MockWebServer()
+    private val ncApiCoroutines: NcApiCoroutines = mock()
+    private val progressListener: OnDataTransferProgressListener = mock()
+    private lateinit var client: OkHttpClient
+    private lateinit var user: User
+    private var successCalls = 0
+
+    @Before
+    fun setUp() {
+        server.start()
+        client = OkHttpClient.Builder()
+            .retryOnConnectionFailure(false)
+            .connectTimeout(TIMEOUT_SECONDS, TimeUnit.SECONDS)
+            .readTimeout(TIMEOUT_SECONDS, TimeUnit.SECONDS)
+            .build()
+        user = User(
+            id = 1,
+            userId = "alice",
+            username = "alice",
+            token = "token",
+            baseUrl = server.url("/").toString().trimEnd('/')
+        )
+    }
+
+    @After
+    fun tearDown() {
+        server.shutdown()
+    }
+
+    @Test
+    fun `does not throw and sends no request when the upload was never started`() {
+        uploader().abortUpload { successCalls++ }
+
+        assertEquals(0, server.requestCount)
+        assertEquals(0, successCalls)
+    }
+
+    @Test
+    fun `does not throw and does not report success when the connection drops`() {
+        val uploader = startedUploader()
+        server.enqueue(MockResponse().apply { socketPolicy = SocketPolicy.DISCONNECT_AFTER_REQUEST })
+
+        uploader.abortUpload { successCalls++ }
+
+        assertEquals(0, successCalls)
+    }
+
+    @Test
+    fun `does not throw and does not report success on a server error`() {
+        val uploader = startedUploader()
+        server.enqueue(MockResponse().setResponseCode(SERVER_ERROR))
+
+        uploader.abortUpload { successCalls++ }
+
+        assertEquals(0, successCalls)
+    }
+
+    @Test
+    fun `reports success when the upload folder is already gone`() {
+        val uploader = startedUploader()
+        server.enqueue(MockResponse().setResponseCode(NOT_FOUND))
+
+        uploader.abortUpload { successCalls++ }
+
+        assertEquals(1, successCalls)
+    }
+
+    @Test
+    fun `reports success when the upload folder is deleted`() {
+        val uploader = startedUploader()
+        server.enqueue(MockResponse().setResponseCode(NO_CONTENT))
+
+        uploader.abortUpload { successCalls++ }
+
+        assertEquals(1, successCalls)
+    }
+
+    @Test
+    fun `does not throw when the success callback throws`() {
+        val uploader = startedUploader()
+        server.enqueue(MockResponse().setResponseCode(NO_CONTENT))
+
+        uploader.abortUpload { throw IllegalStateException("callback failed") }
+    }
+
+    @Test
+    fun `does not throw when the success callback throws for a folder that is already gone`() {
+        val uploader = startedUploader()
+        server.enqueue(MockResponse().setResponseCode(NOT_FOUND))
+
+        uploader.abortUpload { throw IllegalStateException("callback failed") }
+    }
+
+    private fun uploader() = ChunkedFileUploader(client, user, progressListener, ncApiCoroutines)
+
+    /** Runs a rejected upload so the uploader knows its upload folder, then drops the recorded requests. */
+    private fun startedUploader(): ChunkedFileUploader {
+        val file = tempFolder.newFile("test.txt").apply { writeBytes(ByteArray(FILE_SIZE)) }
+        server.enqueue(MockResponse().setResponseCode(CREATED))
+        server.enqueue(MockResponse().setResponseCode(NOT_FOUND))
+        server.enqueue(MockResponse().setResponseCode(FORBIDDEN))
+        val uploader = uploader()
+        uploader.upload(file, "text/plain".toMediaType(), "/Talk/test.txt")
+        repeat(server.requestCount) { server.takeRequest(1, TimeUnit.SECONDS) }
+        return uploader
+    }
+
+    companion object {
+        private const val FILE_SIZE = 5
+        private const val TIMEOUT_SECONDS = 10L
+        private const val CREATED = 201
+        private const val NO_CONTENT = 204
+        private const val FORBIDDEN = 403
+        private const val NOT_FOUND = 404
+        private const val SERVER_ERROR = 500
+    }
+}