Hi,
I notice that some files cannot be deleted or updated in a 7zip archive but can be deleted/updated in other compression archive methods such as rar & zip.
Does anyone know why this is? Is there a way around this?
Thanks.

It would seem to be a problem with 7zip - see the 2nd FAQ - Frequently Asked Questions (FAQ)

Originally Posted by Digerati

It would seem to be a problem with 7zip - see the 2nd FAQ - Frequently Asked Questions (FAQ)

Thank you Digerati.

Here is a quote from the link you gave me:

Why do the add, delete and update operations not work for some existing archives?

The current version of 7-Zip can't execute some operations with .7z archives that have been created with the "solid" option switched on. You can disable solid mode with -ms=off switch in command line