The Following URL is not valid :

Have you verified all permissions on the site are correct? If so, I would recreate the Forms Library and try publishing again.

Also, at what step does this message appear in the publishing tool in Infopath? Does it allow you to select the Forms Library to publish to or does it not even connect to the site?

bureshd,
thanks for reply
it doesnt even connect the site.
the permission are correct & i also tried different forms library & new library it doent even try to connect to the site.

I am still leaning towards a permissions issue, specifically in the site that contains your forms library. I am assuming Infopath services is running? Also, have you published forms to this site before or other location within Sharepoint?

i have published many infopath before to this site before & i am the farm administrator.
last week while working with MS on other issue, we extended the webapplication on port 81,th
 e URl of port 81 worked for the infopath publishing,instead of actual port site 80 . so i deleted the port81 site from IIS but still i see this error on actual site saying "Following URl is not valid url" & site works fine with out any problem

while testing we also created site collection under sites, i deleted that testing site collection too, but i still see the error.

so any clue ?