After upgrade, Geary 0.13.0 cannot connect to existing accounts (set up with 0.12.4)

Bug summary

After upgrading from 0.12.4 to 0.13.0, Geary cannot connect to either of my two accounts. It displays a red banner "Account problem -- Geary encountered a problem connecting to an account." If i click on "Details," it shows the following:

Geary version: 0.13.0
GTK version: 3.22.30
Desktop: ubuntu:GNOME
Account id: ***@gmail.com
Account provider: GEARY_SERVICE_PROVIDER_GMAIL
Service type: GEARY_PROTOCOL_IMAP
Service host: imap.gmail.com
Error type: GIOError 38
Message: Could not connect to imap.gmail.com: Network is unreachable
Back trace:
 - _init
 - g_simple_proxy_resolver_set_uri_proxy
 - g_task_attach_source
 - _init
 - g_simple_proxy_resolver_set_uri_proxy
 - g_task_attach_source
 - _init
 - g_simple_proxy_resolver_set_uri_proxy
 - g_task_attach_source
 - _init
 - g_simple_proxy_resolver_set_uri_proxy
 - g_task_attach_source
 - _init
 - g_simple_proxy_resolver_set_uri_proxy
 - g_task_attach_source
 - g_socket_address_enumerator_next_finish
 - g_simple_proxy_resolver_set_uri_proxy
 - g_task_attach_source
 - g_proxy_address_get_uri
 - g_simple_proxy_resolver_set_uri_proxy
 - g_simple_proxy_resolver_set_uri_proxy
 - g_main_context_dispatch
 - g_main_context_dispatch
 - g_main_context_iteration
 - g_application_run
 - _init
 - __libc_start_main
 - _init

About you

Geary version: 0.13.0
Installation method: PPA for Ubuntu 18.04
Your desktop: GNOME
Your operating system and version: Ubuntu 18.04.2
Email provider: Gmail and another one

Steps to reproduce

Connect to Internet and launch Geary

What is the current bug behavior?

Geary shows the banner "Account problem -- Geary encountered a problem connecting to an account."

Geary does not download new messages.

What is the expected correct behavior?

Download new mail normally.

Relevant logs and/or screenshots

(Paste any relevant logs - please use code blocks (```) to format console output, logs, and code as it's very hard to read otherwise. If the bug is a crash, please obtain a stack trace and attach it to this bug.)