Cannot Copy and paste from WhatsApp and Messages app into Calendar after iOS 27

It is not clear from your post exactly what you are trying to copy and paste from WhatsApp or Messages into the Calendar app.

Could you please clarify what you are attempting to transfer—is it plain text, an event, a date/time, a location, an image, or some other type of content?

Also, please mention which calendar account you are using with the Calendar app. For example, is it iCloud, Google, Outlook/Microsoft, Yahoo, AOL, or another calendar service?

These details are important because the behaviour can differ depending on the type of content being copied and the calendar account or service being used.

Without this information, I cannot accurately understand or reproduce the issue on my own device. If you provide the exact steps you are following, along with the type of content and calendar account involved, I can try to replicate the same scenario and determine whether it is expected behaviour or a bug.

Taijiboy wrote:

After updating to IOS 27,

Not every issue an individual encounters on their device can be attributed to an iOS update. iOS 27 or later may have coincided with what you are experiencing, but that does not mean the issue was triggered by iOS. Coincidence in timing is not, by itself, evidence of causation.

If the update itself were the root cause, then every device running that same version of iOS would exhibit the identical problem. In such a scenario, the forums would be flooded with countless posts reporting the same malfunction, creating an unmistakable wave of complaints that no one could possibly overlook.

The absence of such widespread reports strongly indicates that the issue is not a general, system-wide problem with iOS 27 or later, but rather something specific to the individual device, its configuration, installed apps, settings, hardware, or another interacting factor.

In short: iOS 27 or later may be a coincidence in timing, but there is no basis to conclude that iOS itself triggered the problem simply because the issue appeared after the update.