>>>I have a table where the key field is index a candidate index and field a want change is a regular index. I get the message
>>>

>>>Failed to update table,  Unique index violation
>>>

>>>The error number is 1884. How do I change the second value, i,e, from a "B" to an"A"?
>>
>>No, you want to update a field that is involved in Primary or Candidate index :-)
>>And that violates the rule.
>
>I know why I get the message, my question is there a way around the problem,

And I knew it also :-)
Just change the index, make it regular.