diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/content/UploadContentWorker.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/content/UploadContentWorker.kt
index 1ce805bb66..c5a91cbd9e 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/content/UploadContentWorker.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/content/UploadContentWorker.kt
@@ -161,6 +161,10 @@ internal class UploadContentWorker(val context: Context, params: WorkerParameter
                 var uploadedFileEncryptedFileInfo: EncryptedFileInfo? = null
 
                 return try {
+                    // Compressor library works with File instead of Uri for now. Since Scoped Storage doesn't allow us to access files directly, we should copy
+                    // it to a cache folder by using InputStream and OutputStream.
+                    // https://github.com/zetbaitsu/Compressor/pull/150
+                    // As soon as the above PR is merged, we can use attachment.queryUri instead of creating a cacheFile.
                     var cacheFile = File.createTempFile(attachment.name ?: UUID.randomUUID().toString(), ".jpg", context.cacheDir)
                     cacheFile.parentFile?.mkdirs()
                     if (cacheFile.exists()) {