Pratik, I replaced sidebar.php and that fixed the problem. Thanks.
I also had another issue that I was able to resolve but I think you should know about it. After the update there were two header images, one on top of the other. I went into Customize/Header Image and removed the image so that it says No Image Set. It now displays a header image correctly.
When you issue the new update can I assume I will see the header image disappear until I reset it in Customize? Is there a better way for me to deal with this two header image problem while I’m waiting for the update?