In 'Address Book' Select name of address book eg: 'Personal Address Book' Whilst mouse pointer is hovering over the name of address book, you will see a 3 dot icon suddenly display on the right side - click on the 3 dot icon to see drop down options and select 'Export'

Choose where to save it. Type prefered 'file name' Save as Type: Choose option you require. click on 'Save'.

You didn't tell us anything about phone or account, so I'll just give generic advice. If your account is gmail, you can create a csv export of your thunderbird addressbook and on google contact, you can import the addresses.

Thanks Toad-Hall that was very useful. I did as you said and exported address book to a .csv file. I emailed this so I could pick up on my phone and downloaded to phone. I then went to contacts app and tried to import. But an error message came up that just said there was a problem.

I have a Samsung Android phone. I use the basic Contacts and Mail apps that were already on the phone.

When Contacts ask me where to import from I can see the .csv file and select it. It then gives me three options: Samsung account/Phone/Google. I've tried the first two options with same error message.

I've also gone back to laptop and created a vcard file, but again I get the same error message.when I try to import to Contacts.

Do you have any idea what is going wrong? Thanks.

Try info at this link to get .vcf file on phone. https://www.youtube.com/watch?v=pi1k907oLaE

Thanks Toad-Hall. That's what I did! But it wouldn't import and there was an unhelpful error message.

However I found a workaround by exporting from Thunderbird and importing into Gmail, and then exporting merged address book from Gmail and importing into Contacts. I don't know why using Gmail as an intermediary made a difference.