I just uninstalled and reinstalled the iOS companion app to clear all settings. The I launch it now, I get the initial screen with the continue button on the bottom. I click continue and the second screen starts to load and the app immediately crashes.
I have rebooted my phone, and uninstalled and reinstalled the app.
I just tried to uninstall the app, reboot my phone and reinstall the app. Still crashed
IPhone XR
IOS 13.5
Any suggestions?
I launched the app on my iPad and cleared the settings and tried to connect back to hass.io and now it says “failed to build api URL.”
Same here. Looking for solution…
I had the same problem. I needed to add an internal_url and an external_url in my config under the homeassistant: section. Then restart HASS so that config is reloaded. After that the app worked again.
The above solution worked for me. You can read more about it here in their docs: https://companion.home-assistant.io/docs/troubleshooting/faqs
I went into Home Assistant General Settings and added the internal and external URL. Reboot the Pi. Still didn’t work. Woke up this morning and tried it again, and it let me set up the app. I am really confused. But I’ll go with it.
The above solution did not work for me, after uninstalling the app and re-installing it, it crashes when hitting “Continue”. iOS 13.4.1
I added the internal_url and external_url values in the settings, and it didn’t work for me either. Till I woke up this morning. Which really makes no sense, but I’ll go with it.
I could connect if I first disabled WiFi, connect and login to HA in the app. Afterwards re-activating WiFi and it still works fine!
Are you using a router with openWRT on it by any chance?
Using Ubiquity Unifi Security Gateway 3P
Found another solution that worked for me. Disable WiFi and reopen then app. While the next screen shows up where you can put in the URL, just reconnect to your WiFi and put in the URL and click next.
This solved at least my problem.
HERO! thanks
WOOT! Thanks! This also fixed mine 
This is what I did too.
I have a similar router to @Johan_Nolen but mine is a Ubiquiti Dream Machine which has an integrated ISG. Causation or just correlation? 
Turning WiFi off got me past the crash but failed at auth with a “response status code was unacceptable 404”.
Connecting on a local network using IP address and tried two different users, one with 2FA.
New install on ipad running 13.5. BTW, there are no url config options in settings, just Siri and running in background.
I took Home Assistant offline by restarting it, entered the URL manually and it also worked.So I guess it does have something to do with auto discovery of Home Assistant instances.