(Android) uploads: PlatformException with "Can't handle the provided file type."

[chrisbobbe]

A user writes to support@:

We just started using zulip after you approved sponsorship for our non profit. Heartfelt thank you for that. We, however aren't able to attach any image in zulip app. It throws an error. Attached is the screenshot. Can you please guide us what is the issue ?

Here's the error dialog from the user's screenshot:

More details from the user:

• App version 0.0.27
• Samsung Galaxy S20 FE on One UI 5.1 based on Android 13

They also sent a video showing that this error dialog appears (identically) when they press the paperclip (upload-file) button or the picture (upload-media) button. It appears immediately when they press the button; a "file explorer" interface isn't offered before the dialog appears. The video shows the camera (upload-from-camera) button working as expected without errors.

We should debug this so that the buttons work, if that's within our control, otherwise, to give an actionable error message that makes sense to users.

---

Reading the file_picker implementation, which we use for the paperclip and picture buttons, I see that this error happens when a intent.resolveActivity call returns null:

    private void startFileExplorer() {
        final Intent intent;

        // Temporary fix, remove this null-check after Flutter Engine 1.14 has landed on stable
        if (type == null) {
            return;
        }

        if (type.equals("dir")) {
            intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
        } else {
            if (type.equals("image/*")) {
                intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
            } else {
                if(Build.VERSION.SDK_INT >= 19) {
                    intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
                } else {
                    intent = new Intent(Intent.ACTION_GET_CONTENT);
                }
                intent.addCategory(Intent.CATEGORY_OPENABLE);
            }
            final Uri uri = Uri.parse(Environment.getExternalStorageDirectory().getPath() + File.separator);
            Log.d(TAG, "Selected type " + type);
            intent.setDataAndType(uri, this.type);
            intent.setType(this.type);
            intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, this.isMultipleSelection);
            intent.putExtra("multi-pick", this.isMultipleSelection);

            if (type.contains(",")) {
                allowedExtensions = type.split(",");
            }

            if (allowedExtensions != null) {
                intent.putExtra(Intent.EXTRA_MIME_TYPES, allowedExtensions);
            }
        }

        if (intent.resolveActivity(this.activity.getPackageManager()) != null) {
            this.activity.startActivityForResult(intent, REQUEST_CODE);
        } else {
            Log.e(TAG, "Can't find a valid activity to handle the request. Make sure you've a file explorer installed.");
            finishWithError("invalid_format_type", "Can't handle the provided file type.");
        }
    }

So it looks like there's an issue accessing the file-picker UI; its activity isn't being found.

I expect the type to be */* for the upload-file codepath and image/*,video/* for the upload-media codepath.

UPDATES:

• We should consider switching from file_picker to the first-party plugin file_selector; this is Switch from file_picker package to first-party file_selector and/or image_picker #855
• We could try adding a <queries> element for ACTION_OPEN_DOCUMENT, in file_picker and/or our app, on the theory that "package visibility filtering" is why the file-picker UI isn't being opened for this user. Discussion: #mobile-team > #F1446 Android upload issue @ 💬

[gnprice]

Hmm. Looks like checking with resolveActivity first before attempting startActivityForResult is exactly what the Android docs recommend:
https://developer.android.com/guide/components/intents-common

so file_picker is doing the right thing there.

From lower down in that doc, the use of Intent.ACTION_OPEN_DOCUMENT looks fine (though possibly Intent.ACTION_GET_CONTENT would be better, not sure). ACTION_PICK isn't recommended there for images — it suggests again using ACTION_GET_CONTENT or ACTION_OPEN_DOCUMENT — but that can't explain the failure on the "upload file" button.

Debugging questions for the user, which might help us investigate:

• Do they have a "files" app on their phone? What is it called? Can they send us a screenshot of that app, and/or what the app's icon looks like on their home screen?
• Are there other apps they use with similar "attach a file" functionality, and does that functionality work there?
• Do they have separate "profiles" on their phone, like a work profile and a personal profile?

[gnprice]

From looking in the file_picker tracker, here's an old issue with similar symptoms:

• Crash 2.0.7 / Android / image / "Make sure you've a file explorer installed" miguelpruivo/flutter_file_picker#440

but it was fixed in 2020.

And here's a report which caused me to think of the "profiles" hypothesis:

• Facing problem with file picker on android 10 miguelpruivo/flutter_file_picker#429 (comment)

If the user is running Zulip in a profile that does not have access to a file explorer app, then that would explain it.

[Quelaan1]

@gnprice

There is no PR on this issue, I assume it's open and unsolved. I'm starting to work on this now.

I'll make sure to read the contribution guide first.

Thanks

[chrisbobbe]

Added a note to the issue description about a possible fix. And thanks @Quelaan1, I've just assigned this to you.

[Quelaan1]

Could you please unassign me from this issue? I unfortunately no longer have the bandwidth to work on it. Thanks! @chrisbobbe