Multiple errors on WMT for URL that doesnt exist anymore

[jaxx]

Hello everyone.

We did a few upgrades on one of our websites.
The categories URL stay the same. the problem is Google indexed the aspx urls and now can’t find them.
* The aspx urls were different before, we use a different aspx urls

The result for now is a Hugh amount of errors because WMT cannot find these urls.

My question:
1. What will be the proper solution for this problem?
I had the same problem with some static cat pages; I just redirected them to the home page. In this case the error is 10 times bigger so I am not sure if this will be the best solution.
What do you think?

2. do you think these error could have a negative effect on my website ranking ?

[zico82]

1) Use the URL removal tool in WMT

2) Google states that 404's dont generally harm your listings but can hurt internal linking.

[sandysan9]

Erro 301 code will help you in this, which will do the Perfect URL redirect work