updates error

for several weeks, I have been unable to update knime. What is causing this to error? I get the below message.

 

Some sites could not be found.  See the error log for more detail.
No repository found at http://docs.pervasive.com/products/DataFlow/updates.
No repository found at http://docs.pervasive.com/products.

It seems you have entered these update sites manually and they don't exist any more. These are non of our update sites. Try disabling or removing these sites in the preferences (Install/Update -> Available Software Sites).

I have the same. If those sites are not availabe as well? They look as part of KNIME.

Some sites could not be found.  See the error log for more detail.
No repository found at http://tech.knime.org/update/bison.
No repository found at http://tech.knime.org/update/bisonet.

Those were updates sites of an old internal project, they were never publicly available. They don't exist any more for several years by now.

that was easy enough. 

much obliged!