diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/content/ContentAttachmentData.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/content/ContentAttachmentData.kt
index 933657b2fb..0d8ef2c52b 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/content/ContentAttachmentData.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/content/ContentAttachmentData.kt
@@ -30,7 +30,7 @@ data class ContentAttachmentData(
         val exifOrientation: Int = ExifInterface.ORIENTATION_UNDEFINED,
         val name: String? = null,
         val path: String,
-        val mimeType: String,
+        val mimeType: String?,
         val type: Type
 ) : Parcelable {
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/message/VideoInfo.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/message/VideoInfo.kt
index a7d4708d33..da247810cb 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/message/VideoInfo.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/message/VideoInfo.kt
@@ -25,7 +25,7 @@ data class VideoInfo(
         /**
          * The mimetype of the video e.g. "video/mp4".
          */
-        @Json(name = "mimetype") val mimeType: String,
+        @Json(name = "mimetype") val mimeType: String?,
 
         /**
          * The width of the video in pixels.
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/attachments/MXEncryptedAttachments.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/attachments/MXEncryptedAttachments.kt
index 5f90b636ac..503bf8e4ff 100755
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/attachments/MXEncryptedAttachments.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/attachments/MXEncryptedAttachments.kt
@@ -49,7 +49,7 @@ object MXEncryptedAttachments {
      * @param mimetype the mime type
      * @return the encryption file info
      */
-    fun encryptAttachment(attachmentStream: InputStream, mimetype: String): EncryptionResult {
+    fun encryptAttachment(attachmentStream: InputStream, mimetype: String?): EncryptionResult {
         val t0 = System.currentTimeMillis()
         val secureRandom = SecureRandom()
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/content/FileUploader.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/content/FileUploader.kt
index 209f03ad9d..2f4e991e62 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/content/FileUploader.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/content/FileUploader.kt
@@ -43,9 +43,9 @@ internal class FileUploader @Inject constructor(@Authenticated
 
     suspend fun uploadFile(file: File,
                            filename: String?,
-                           mimeType: String,
+                           mimeType: String?,
                            progressListener: ProgressRequestBody.Listener? = null): ContentUploadResponse {
-        val uploadBody = file.asRequestBody(mimeType.toMediaTypeOrNull())
+        val uploadBody = file.asRequestBody(mimeType?.toMediaTypeOrNull())
         return upload(uploadBody, filename, progressListener)
     }
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/send/LocalEchoEventFactory.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/send/LocalEchoEventFactory.kt
index 0fed1ca6f5..7a935783cf 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/send/LocalEchoEventFactory.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/send/LocalEchoEventFactory.kt
@@ -251,7 +251,7 @@ internal class LocalEchoEventFactory @Inject constructor(
                 type = MessageType.MSGTYPE_AUDIO,
                 body = attachment.name ?: "audio",
                 audioInfo = AudioInfo(
-                        mimeType = attachment.mimeType.takeIf { it.isNotBlank() } ?: "audio/mpeg",
+                        mimeType = attachment.mimeType?.takeIf { it.isNotBlank() } ?: "audio/mpeg",
                         size = attachment.size
                 ),
                 url = attachment.path
@@ -264,7 +264,7 @@ internal class LocalEchoEventFactory @Inject constructor(
                 type = MessageType.MSGTYPE_FILE,
                 body = attachment.name ?: "file",
                 info = FileInfo(
-                        mimeType = attachment.mimeType.takeIf { it.isNotBlank() }
+                        mimeType = attachment.mimeType?.takeIf { it.isNotBlank() }
                                 ?: "application/octet-stream",
                         size = attachment.size
                 ),
diff --git a/vector/src/main/java/im/vector/riotx/features/attachments/AttachmentsMapper.kt b/vector/src/main/java/im/vector/riotx/features/attachments/AttachmentsMapper.kt
index 5e843fcdfd..4b51c548a7 100644
--- a/vector/src/main/java/im/vector/riotx/features/attachments/AttachmentsMapper.kt
+++ b/vector/src/main/java/im/vector/riotx/features/attachments/AttachmentsMapper.kt
@@ -18,6 +18,7 @@ package im.vector.riotx.features.attachments
 
 import com.kbeanie.multipicker.api.entity.*
 import im.vector.matrix.android.api.session.content.ContentAttachmentData
+import timber.log.Timber
 
 fun ChosenContact.toContactAttachment(): ContactAttachment {
     return ContactAttachment(
@@ -29,6 +30,7 @@ fun ChosenContact.toContactAttachment(): ContactAttachment {
 }
 
 fun ChosenFile.toContentAttachmentData(): ContentAttachmentData {
+    if (mimeType == null) Timber.w("No mimeType")
     return ContentAttachmentData(
             path = originalPath,
             mimeType = mimeType,
@@ -40,6 +42,7 @@ fun ChosenFile.toContentAttachmentData(): ContentAttachmentData {
 }
 
 fun ChosenAudio.toContentAttachmentData(): ContentAttachmentData {
+    if (mimeType == null) Timber.w("No mimeType")
     return ContentAttachmentData(
             path = originalPath,
             mimeType = mimeType,
@@ -51,16 +54,17 @@ fun ChosenAudio.toContentAttachmentData(): ContentAttachmentData {
     )
 }
 
-fun ChosenFile.mapType(): ContentAttachmentData.Type {
+private fun ChosenFile.mapType(): ContentAttachmentData.Type {
     return when {
-        mimeType.startsWith("image/") -> ContentAttachmentData.Type.IMAGE
-        mimeType.startsWith("video/") -> ContentAttachmentData.Type.VIDEO
-        mimeType.startsWith("audio/") -> ContentAttachmentData.Type.AUDIO
-        else                          -> ContentAttachmentData.Type.FILE
+        mimeType?.startsWith("image/") == true -> ContentAttachmentData.Type.IMAGE
+        mimeType?.startsWith("video/") == true -> ContentAttachmentData.Type.VIDEO
+        mimeType?.startsWith("audio/") == true -> ContentAttachmentData.Type.AUDIO
+        else                                   -> ContentAttachmentData.Type.FILE
     }
 }
 
 fun ChosenImage.toContentAttachmentData(): ContentAttachmentData {
+    if (mimeType == null) Timber.w("No mimeType")
     return ContentAttachmentData(
             path = originalPath,
             mimeType = mimeType,
@@ -75,6 +79,7 @@ fun ChosenImage.toContentAttachmentData(): ContentAttachmentData {
 }
 
 fun ChosenVideo.toContentAttachmentData(): ContentAttachmentData {
+    if (mimeType == null) Timber.w("No mimeType")
     return ContentAttachmentData(
             path = originalPath,
             mimeType = mimeType,