Hello,
First of all thanks for choosing our Theme, we are glad to be you in the WoodMart WordPress family :-)
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I saw the screenshot you attached.
Try to do the following to update the theme:
1. Go to Dashboard -> WoodMart -> Theme License and deactivate the theme.
2. Go to Dashboard -> Updates and click on Check Again.
3. Activate the theme with your purchase code again.
4. Try to update the theme via Appearance -> Themes or via Dashboard -> Updates.
If it does not help, make the full backup of your site and we shall do it for your via FTP.
Best Regards.