WhatsApp has long been protecting private conversations by backing them up on phones as well as on the cloud.
You can easily restore the cloud backup to get old messages back, even after switching to a new phone.
But, this only works as long as you're on the same platform; if you go from Android to iOS, the messages aren't restored.
Here's a solution.
WhatsApp backups don't officially migrate across platforms
On Android phones, WhatsApp creates cloud backup of chats on Google Drive, while on iOS, the platform uses iCloud for the same.
Now, owing to this difference, the backups aren't restored when a user decides to switch from an Android to iOS device (or vice-versa).
Even transferring the local backup from one platform to another doesn't work due to different formats in use.
Using third-party transfer solution is the only way out
While there is no official way to migrate chat history from Android to iOS, there are several third-party migration platforms available to do the job.
The best option on the list is dr.fone, a Windows/Mac program that lets you create a backup of all WhatsApp data, from messages to media, on a PC and then transfer and restore it on the second phone.
First, you'd have to create a backup of WhatsApp data
Install and launch the dr.fone app on your PC.
Then, from the interface of the app, navigate to Restore Social App > Backup WhatsApp Messages and connect your source phone to backup all WhatsApp data on your PC.
Follow the prompts in between to complete the backup process and get a complete single backed-up file of all the data in the end.
Then, transfer and restore that backup on the second device
After creating a backup, head over to Restore Social App again but click either on 'Restore WhatsApp Messages to iOS device' or 'Restore WhatsApp messages to Android device' - depending on the platform you are migrating to.
Then, select the backup file, connect the target device, and log into WhatsApp (when prompted) to transfer and restore all WhatsApp messages and media on it.
Finally, restart the device
After the restoration is done, simply restart the iOS/Android device and launch WhatsApp again to get access to all the conversations restored from the source phone.