Many thanks for responding! De-selecting the California state return from e-filing did indeed make it possible to e-file the federal return. The state return still produces a dialog box that says updates are available and must be applied before I can e-file, so it may be necessary to file by paper.
I am impressed (and grateful) that someone in the community chose to respond, but I am totally unimpressed with Intuit support. There is clearly an issue with the software; telling users to talk among themselves to figure out a workaround is unacceptable.
