"Add document" link is missing after migrating document libraries from SharePoint 2007 to SharePoint 2010

After we had migrated from SharePoint 2007 to SharePoint 2010 we noticed that some document libraries didn't have the Add document" link and the small tick box. The following screen shots show comparison between a working and non-working document library:

Working Document Library:

Non-working Document Library:

At this point, the quick fox was to create a new standard view and make it as the default view. I will try to investigate the issue and update the post.

HTTP 404 Not Found when opening a file that has "+" in its name in Internet Explorer from SharePoint Document Library

A user came to me complaining that she is getting HTTP 404 Not Found in Internet Explorer when clicking a pdf document in a SharePoint Document Library to view it, as shown below:

Note: SharePoint won't allow you to upload any documents that have the following special characters as shown in the screen shot below:

After further investigation and testing, I came to the following conclusion. Although you can upload a document to a SharePoint Document Library that has "+" sign in its name (ex. filename+). However, when you try to view or open the document in a web browser we get the HTTP 404 error. I believe this is "By Design" and the workaround would be to rename the file by removing the "+" sign and users would be able to view the document in a web browser.