Hello

 I found the error!! I feel very sheepish and a bit embarrased for causing all this fuss, but here it is:

In order to check I had transfered everything correctly:

I had put comments everywhere, start and end. But I had accidently deleted the end, of one of the comments, consequently it was not fully closed correctly.  Ooops!!!

I was consentrating on ensuring that I had transfered all settings over correctly, looking only at the settings that I overlooked the rest.

I was working in notepad which does not show up colours of coding, so this error was not immediately noticeable.  It was only when I printed web.config out and inspected each line to compare.

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At last I have been successful the 4.3.5 upgrade it has worked. Except for one upgrade install error:

Install\Module\Reports_4.3.1_Source.zip:  Error!

But I will look into that later. Unless someone has a quick solution.

Thanks for all your help and support guys.

Lynn