I had the same problem. I attempted to correct some of them, but actually as far as I know, these errors are not critical and can be ignored.

>I inherited an ASP.Net application that contains a master page. The application runs fine but when I look at the master page in Source view, I see a lot of the tags marked with red or green under lines showing errors in the source.
>
>The errors consist of:
> -The name contains uppercase characters, which is not allowed.
> -Attribute values must be enclosed in quotation marks.
> -Attribute 'bgcolor' is considered outdated. A newer construct is recommended.
> -Attribute 'height' is considered outdated. A newer construct is recommended.
>
>There are hundreds of these errors and warnings. Should I attempt to correct all of these errors? Is there an easy way to do this?
>
>I believe that this master page was originally a classic asp page that was made into a asp.net master page. Below is a small example of some of the syntax used in the source. What would be the best way to handle these issues?
>
>

><TABLE cellSpacing=0 cellPadding=10 width=579 border=0>
>     <TBODY>
>         <TR>
>                      <TD width=577>
>
>                          <form id="form1" runat="server">
>                        <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
>                              </asp:ContentPlaceHolder>
>                        </form>
>                      </TD>
>                    <TR>
>                      <TD bgColor=#ebebeb colSpan=8 height=10>
>                        </TD>
>          </TR>
>    </TBODY>
></TABLE>
>

>
>Thanks,
>
>Jerry