It seems like the second time this error happened to me, when trying to estimate ACBC utilities within SSI Web v8.2.4.
Since there is no hint, what the root of the problem is, the only work around I could find out is, to setup a completely new survey and to copy and paste all the pages and every detail of the ACBC-wording and design.
This is not fun, but works without problem. When I estimate ACBC utilites with HB in the new survey (the same data as before) the error does not appear again.
Did anybody have the same error and found out how to avoid the error in first place?