I've been converting an ASP VB.Net 1.1 project to .Net 3.5. Part of that process has involved moving a whole bunch of Crystal Reports. During the conversion, I hit the dreaded "Unable to find the report in the manifest resources. Please build the project, and try again." error.
I did countless searches and found nothing that helped me with this particular problem, but I eventually discovered that, in the code behind, the ResourceName property needs to return a fully qualified path to the report, including any folders they may be in, e.g. "Report Formatsblah.rpt". This is not required in .Net 1.1/Crystal 9, hence it was working fine with the original project, but not in the converted one.
That’s not always the solution for this error message, but it worked for me.
On a general note, Crystal Reports has to be the worst product with the worst support and the worst error reporting I've ever had the misfortune to work with. What I find amazing is that, whenever I hit a problem with CR (which is frequently), I do the usual Google search, find hundreds - if not thousands - of folk with the same issue and there's either no solution or about 10,000 possible solutions. Actually, that's not quite fair. There's normally one common suggested fix for almost every query - don't use Crystal Reports!