Forum Discussion
Merge Function Throwing errors if there is a NULL value
Like I said, sounds like a bug. Do you have the install file for the previous version of Power BI. That may be the best chance of you making the deadline.
The root source of the error was burried in the left side of the left outer join, below the 999 preview rows. The problem was that I had concatenated three columns together, which included null values. If I concatenate 3 columns together with one or all three values being null then I got the error message:
Expression.Error: We cannot conver the value null to type Logical.
Details:
Value=
Type=Type
This expression error does not cause the table to fail until it is executed as part of a join, making it very hard to identify the step that caused the error.
Your frustration at this made me laugh. I know the feeling all too well! Glad you found a fix.
For anyone else who's had this problem, I've also had this error, caused by null values being fed into a conditional column. I had appended two tables. For one of the columns, Table 1 had empty cells represented as "", Table 2 had them as null. In the appended table, this column was used as a condition for a conditional column (if value), but it didn't like the null values so threw up this error. I fixed by replacing the null values in Table 2 with "".
It's unfortunate these error messages are so vague. Took a bit of trial and error to figure this one out.
