Question: I'm upgrading a website from Sitecore 6.5 to Sitecore 7. The upgrade has been smooth and I was able to get everything up and running except for WFFM.

After installing WFFM 2.3 latest, I keep getting the error

> 
> Could not load file or assembly 'HtmlAgilityPack, Version=1.4.0.0,
>  Culture=neutral, PublicKeyToken=bd319b19eaf3b43a' or one of its
>  dependencies. The located assembly's manifest definition does not
>  match the assembly reference. (Exception from HRESULT: 0x80131040)
> 
> 
> 

Sitecore 7 upgrades it's 3rd party dll for HtmlAgilityPack to 1.4.3, but WFFM seems to still reference 1.4.0

Has anyone dealt with this? Am I missing something?

Thanks for the help.

Answer: 
This is a known bug for Sitecore. Check out [this link](http://sdn.sitecore.net/Products/Web%20Forms%20for%20Marketers/Web%20Forms%20for%20Marketers%202,-d-,3/Release%20Notes/Known%20issues.aspx) for a fix (382886).
I've run into HtmlAgilityPack version mismatches during previous Sitecore upgrades when WFFM was installed. I've just been able to update the reference by hand to the new file without suffering any consequences.

It seems that a separate team works on WFFM and the work is lagged several months behind the Sitecore core.