BaseMvpActivity.java

@Override
    public void showError(String errorMessage) {
        if (errorMessage == null || errorMessage.trim().isEmpty())
            errorMessage = getString(R.string.default_error_message);
        AlertDialog dialog = new CustomAlertDialogBuilder(this)
                .addMessage(errorMessage)
                .setPositiveButton("OK", DialogInterface::dismiss)
                .build();
        try {
            if (dialog != null) {
                dialogs.add(dialog);

                //Added this line

                if(!isFinishing())
                    dialog.show();
            }
        } catch (Exception e) {
            Crashlytics.logException(e);
        }
    }

    @Override
    public void showMessage(int errorMessage) {
        showMessage(getString(errorMessage));
    }