Error during update to 8.8.4

Got this error. Update does not finish. How to resolve?

Executing frappe.patches.v8_7.update_email_queue_status in site1.local (1bd3e0294da19198)
Traceback (most recent call last):
  File "/usr/lib/python2.7/runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/home/frappe/frappe-bench/apps/frappe/frappe/utils/bench_helper.py", line 94, in <module>
    main()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/utils/bench_helper.py", line 18, in main
    click.Group(commands=commands)(prog_name='bench')
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/commands/__init__.py", line 24, in _func
    ret = f(frappe._dict(ctx.obj), *args, **kwargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/commands/site.py", line 217, in migrate
    migrate(context.verbose, rebuild_website=rebuild_website)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/migrate.py", line 31, in migrate
    frappe.modules.patch_handler.run_all()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/modules/patch_handler.py", line 29, in run_all
    if not run_single(patchmodule = patch):
  File "/home/frappe/frappe-bench/apps/frappe/frappe/modules/patch_handler.py", line 63, in run_single
    return execute_patch(patchmodule, method, methodargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/modules/patch_handler.py", line 83, in execute_patch
    frappe.get_attr(patchmodule.split()[0] + ".execute")()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/patches/v8_7/update_email_queue_status.py", line 7, in execute
    default_email_account = get_default_outgoing_email_account()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/email/smtp.py", line 87, in get_default_outgoing_email_account
    email_account.password = email_account.get_password(raise_exception=False)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/model/base_document.py", line 664, in get_password
    return get_decrypted_password(self.doctype, self.name, fieldname, raise_exception=raise_exception)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/utils/password.py", line 16, in get_decrypted_password
    return decrypt(auth[0][0])
  File "/home/frappe/frappe-bench/apps/frappe/frappe/utils/password.py", line 106, in decrypt
    frappe.throw(_('Encryption key is invalid, Please check site_config.json'))
  File "/home/frappe/frappe-bench/apps/frappe/frappe/__init__.py", line 319, in throw
    msgprint(msg, raise_exception=exc, title=title, indicator='red')
  File "/home/frappe/frappe-bench/apps/frappe/frappe/__init__.py", line 309, in msgprint
    _raise_exception()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/__init__.py", line 282, in _raise_exception
    raise raise_exception(encode(msg))
frappe.exceptions.ValidationError: Encryption key is invalid, Please check site_config.json

Please check the following thread: