An import failure can come from the file, the import route, or events already present in the destination. Start with a separate test calendar, keep the original export, and change one thing at a time.
1. Make sure you have the calendar file
A Google export can arrive as a ZIP containing individual ICS calendars. Extract the ZIP and choose one ICS file in the desktop calendar’s Import & export settings. Renaming a ZIP to .ics does not convert it.
2. Check size and structure
Google’s troubleshooting page specifies a 1 MB import limit. A file above the limit needs smaller parts. Each part must remain a complete VCALENDAR document. Do not cut an ICS file at arbitrary text lines: a repeating event can have exception records elsewhere in the file, and named time zones can have shared definitions.
3. Inspect the events before trying again
Look for missing DTSTART or UID fields, impossible dates, and end times before start times. Passing a local check is useful evidence about the file’s structure, but does not prove that Google will accept it.
4. Check recurrence and destination time zone
CSV has a limited field model. A spreadsheet round trip can turn a repeating series into separate one-off events or omit recurrence information entirely. Use the original ICS when you need to preserve rules and exceptions. If times shift after import, check the destination calendar’s time zone and the event’s DTSTART parameters.
5. Avoid repeated blind imports
Google documents that clicking Import more than once can lead to “Processed zero events.” Check the destination before importing again. Importing to a new temporary calendar makes it easier to see what was actually added and remove the test afterward.
Sources: Google’s import troubleshooting and supported import formats. Reviewed 21 October 2026. CalPorter is independent of Google.