My professor uploaded an unsigned recommendation My question is about letters of recommendation for University of Pittsburgh , graduate studies. My professor uploaded a plain PDF document of the letter over electronic recommendation. Will this create any issues? The document was not signed, but it was not mentioned anywhere to sign the letter of recommendation (which was done in the case if students themselves uploaded the letter)

I am worried.
I wouldn't worry too much about it. 

We're currently in a transitional state between a world of paper documents and a world of electronic documents, and the conventions for digital signatures haven't really converged yet. As such, some people sign on paper and scan, some sign digitally, and some don't sign at all.  If you're dealing with a large institution, they've probably seen it all, and are unlikely to hold it against you.  After all, even if it was signed, what's the likelihood they would actually know what your professor's signature looks like?