Hello:

I was able to resolve this diagnostic by entering the values in 4 fields located under the 'California Like-Kind Exchanges (3840)' section:

1.  Total CA source deferred gain
2.  Apportionment percentage (xx.xxxx)
3.  Properties given up (Crtl+E)
4.  Properties received (Crtl+E) 

As I understand, #2 above is now a mandatory field which may not have been the case in prior years.  Since with my client's return, I did have out of state income, I did have a value to enter in #2. 

For 100%, enter 100.00 if you do not have out of state apportionment.

Check the outcome on Part III, lline 11 of 3840.

Good luck and please let us know if this worked.