When filing a tax return for someone that had 1031'd a property in CA for properties outside CA (one to many), in the year PRIOR to the year I am filing, I received a rejection from CA on the relatively new form 3840  (that's designed to enforce CA's claw-back law to tax gain that accumulated while the property was in CA before the 1031).

The rejection information sent by CA FTB is:

A valid date is required to be entered for each property received or given up
ReturnData/CAForm3840/LikeKindExchangeInfo/PropertyGivenUpAcquiredDate

If I look at the generated form 3840 closely enough, I see the date for the property given up is listed as "16/02/4014"
The entry points to this form come from several places, but the relevant screen is in "Other" on the left, down at "CA Like-Kind Exchanges (3840)".  Looking down at the "Date like-kind property given up was originally acquired" and the date entered is 08/01/2007.  (Note the amount being reported on the form and rejected by CA is double the date entered, 16/02/4014)

I found a workaround posted next, I'm reporting this here just in case anyone else hits this.