Remote Calendar fails to parse iCloud calendar due to malformed ICS

[D1irk]

The problem

When adding an iCloud calendar as a Remote Calendar in Home Assistant, the integration fails to parse the calendar with the error:

Error parsing calendar information: Calendar contents are not valid ICS format
Additional detail: Invalid property line, expected (';', ':') after property name

This suggests the iCalendar data from iCloud contains a malformed property line that doesn't conform to RFC 5545 standards.

Steps to reproduce:

1. Add an iCloud calendar via Remote Calendar integration
2. Wait for initial sync
3. Check logs for the error

Expected: Calendar syncs successfully

What version of Home Assistant Core has the issue?

core-2026.5.2

What was the last working version of Home Assistant Core?

No response

What type of installation are you running?

Home Assistant OS

Integration causing the issue

Remote Calendar

Link to integration documentation on our website

https://www.home-assistant.io/integrations/remote_calendar

Diagnostics information

2026-05-17 18:36:12.020 DEBUG (SyncWorker_9) [ical.compat.make_compat] Extracted PRODID: <re.Match object; span=(30, 188), match='PRODID:-//caldav.icloud.com//CALDAVJ 2616B792//EN>
2026-05-17 18:36:12.157 ERROR (MainThread) [homeassistant.components.remote_calendar.ics] Error parsing calendar information: Calendar contents are not valid ICS format, see the detailed_error for more information
2026-05-17 18:36:12.157 DEBUG (MainThread) [homeassistant.components.remote_calendar.ics] Additional calendar error detail: Invalid property line, expected (';', ':') after property name

Example YAML snippet

Anything in the logs that might be useful for us?

Additional information

No response

[home-assistant]

Hey there @Thomas55555, @allenporter, mind taking a look at this issue as it has been labeled with an integration (remote_calendar) you are listed as a code owner for? Thanks!

Code owner commands

Code owners of remote_calendar can trigger bot actions by commenting:

• @home-assistant close Closes the issue.
• @home-assistant rename Awesome new title Renames the issue.
• @home-assistant reopen Reopen the issue.
• @home-assistant unassign remote_calendar Removes the current integration label and assignees on the issue, add the integration domain after the command.
• @home-assistant add-label needs-more-information Add a label (needs-more-information, problem in dependency, problem in custom component, problem in config, problem in device, feature-request) to the issue.
• @home-assistant remove-label needs-more-information Remove a label (needs-more-information, problem in dependency, problem in custom component, problem in config, problem in device, feature-request) on the issue.

_{^{(message by CodeOwnersMention)}}

---

@D1irk Thanks for reporting this issue!

Before we dive in, please make sure this isn't a duplicate by searching through existing issues. Also check recently closed issues, as your problem might already be fixed but not yet released.

https://github.com/home-assistant/core/issues?q=%20label%3A%22integration%3A%20remote_calendar%22%20
_{^{(message by IssueContext)}}

---

remote_calendar documentation
remote_calendar source
_{^{(message by IssueLinks)}}

[D1irk]

The same calendar works fine when imported via the CalDAV integration (docs).

[allenporter]

Yes, this suggests the iCalendar data from iCloud contains a malformed property line that doesn't conform to RFC 5545 standards.

Do you have an example of the calendar contents that trigger the problem?

[D1irk]

Hi! Thanks for looking into this.
Unfortunately, I can’t share the actual .ics file due to privacy concerns — it contains a lot of personal events. The error logs also don’t pinpoint the specific malformed entry, which makes debugging tricky.
Is there a way to enable more detailed logging (e.g., full ICS content or line-by-line parsing feedback) to help identify the problematic property? That way, I could share just the relevant snippet without exposing sensitive data.

[allenporter]

Hi, one option is to turn up debugging further by editing configuration.yaml and adding this:

logger:
  default: info
  logs:
    ical: debug

[allenporter]

The integration is correctly telling you that the content is invalid -- seems like it is invalid based on the description (missing a ; or : character, required on every content line).

I have a bump that adds some additional detail to the detailed error message to give you the actual content line that was being parsed.

If there is some widespread issue for icloud calendars we can consider a "compat" workaround, but so far i think the integration is working correctly.

[zackpeterson]

I saw the same error when I tried to add my public Apple iCloud calendar with Remote Calendar.

webcal://p40-caldav.icloud.com/published/2/[REDACTED]

DEBUG (SyncWorker_3) [ical.compat.make_compat] Extracted PRODID: <re.Match object; span=(30, 162), match='PRODID:-//caldav.icloud.com//CALDAVJ [REDACTED]//EN>

ERROR (MainThread) [homeassistant.components.remote_calendar.ics] Error parsing calendar information: Calendar contents are not valid ICS format, see the detailed_error for more information

DEBUG (MainThread) [homeassistant.components.remote_calendar.ics] Additional calendar error detail: Invalid property line, expected (';', ':') after property name

I got it to work by finding and updating the problem entries.

I had a few malformed street addresses on events from 2022 and earlier. I think they included line break characters that caused the problem.

1. I downloaded the file with my browser by changing the address protocol from webcal:// to http://.

2. I checked the file using the website https://icalendar.dev/validator/

3. It gave me a clue that pointed to a problem event.

4. I edited that event's location and then tried again.

5. Repeat: Re-download. Re-validate. Update. Retry.

I did several rounds of all that until Remote Calendar would parse the file.