What causes "Could not read backup info. Possibly due to a malformed json file." in MuntashirAkon/AppManager?

Validate backup.json with a JSON parser/validator and fix syntax errors if it was hand-edited.

MuntashirAkon/AppManager · error · BackupException

Could not read backup info. Possibly due to a malformed…

Error message

Could not read backup info. Possibly due to a malformed json file.

What it means

The VerifyOp constructor calls mBackupItem.getInfo() to parse backup.json. If reading or JSON-parsing that file throws an IOException, cleanup() runs and this BackupException is thrown. It means the backup descriptor file is missing, unreadable, or not valid JSON.

Solutions

Validate backup.json with a JSON parser/validator and fix syntax errors if it was hand-edited.
Re-copy the complete backup directory from the source device, including backup.json.
Recreate the backup on the source device if the original file is truncated.
Check file permissions/readability of backup.json for the AppManager process.

Example fix

// before: backup.json with trailing comma
{"flags": "...",}
// after: valid JSON
{"flags": "..."}

Defensive patterns

Strategy: validation

Validate before calling

// Validate backup.json parses before constructing VerifyOp
File f = new File(backupDir, "backup.json");
if (!f.isFile() || f.length() == 0) throw new IllegalStateException("backup.json missing/empty");
try (FileInputStream in = new FileInputStream(f)) {
    new JSONObject(new String(IOUtils.readFully(in))); // throws if malformed
}

Try / catch

try {
    new VerifyOp(backupItem).verify();
} catch (BackupException e) {
    if (e.getMessage().contains("malformed json")) {
        // re-copy or regenerate the backup
    }
}

Prevention

Copy entire backup directories, never individual files.
Never hand-edit backup.json; regenerate via the app instead.
Sanity-check a freshly copied backup by parsing backup.json before deleting the original.

When it happens

Trigger: Constructing VerifyOp (or running verify) on a backup directory where backup.json is absent, truncated, or contains malformed JSON — typically after an interrupted backup or a partial copy.

Common situations: Backing up to SD card/cloud that dropped files during transfer, manually edited backup.json with a syntax error, restoring only part of a backup directory, or file-permission issues making backup.json unreadable.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

AI-assisted analysis of MuntashirAkon/AppManager@0152f468fc (2026-09-12). Data as JSON: /api/errors/26c4190112ea8834. Report an issue: GitHub.

Appendix: source

Thrown at app/src/main/java/io/github/muntashirakon/AppManager/backup/VerifyOp.java:39

    @NonNull
    private final BackupFlags mBackupFlags;
    @NonNull
    private final BackupMetadataV5.Info mBackupInfo;
    @NonNull
    private final BackupMetadataV5.Metadata mBackupMetadata;
    @NonNull
    private final BackupItems.BackupItem mBackupItem;
    @NonNull
    private final BackupItems.Checksum mChecksum;

    VerifyOp(@NonNull BackupItems.BackupItem backupItem) throws BackupException {
        mBackupItem = backupItem;
        try {
            mBackupInfo = mBackupItem.getInfo();
            mBackupFlags = mBackupInfo.flags;
        } catch (IOException e) {
            mBackupItem.cleanup();
            throw new BackupException("Could not read backup info. Possibly due to a malformed json file.", e);
        }
        // Setup crypto
        if (!CryptoUtils.isAvailable(mBackupInfo.crypto)) {
            mBackupItem.cleanup();
            throw new BackupException("Mode " + mBackupInfo.crypto + " is currently unavailable.");
        }
        try {
            mBackupItem.setCrypto(mBackupInfo.getCrypto());
        } catch (CryptoException e) {
            mBackupItem.cleanup();
            throw new BackupException("Could not get crypto " + mBackupInfo.crypto, e);
        }
        try {
            mBackupMetadata = mBackupItem.getMetadata(mBackupInfo).metadata;
        } catch (IOException e) {
            mBackupItem.cleanup();
            throw new BackupException("Could not read backup metadata. Possibly due to a malformed json file.", e);
        }

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