Solution:Step 1: Analyze first rowThe first row is {"ID", "Value"}, but the second row has a null in the first column.Step 2: Understand PromoteAllScalars=falseThis setting disallows promoting null or scalar values as headers.Step 3: Cause of errorNull in data rows can cause header promotion to fail

[Solved] You run this M code:let Source = Table.FromRows({{"ID", "Value"}, {null, 100}}), Promoted = Table.... What is the most probable reason? | Power BI

Power BI - Data Cleaning with Power Query

You run this M code:

let
  Source = Table.FromRows({{"ID", "Value"}, {null, 100}}),
  Promoted = Table.PromoteHeaders(Source, [PromoteAllScalars=false])
in
  Promoted

and get an error. What is the most probable reason?

AThe table has duplicate column names in the first row.

BThe first row contains null values which cannot be promoted as headers.

CThe PromoteAllScalars option is set to true, causing conflicts.

DThe table has more than two columns.

Step-by-Step Solution

Solution:

Step 1: Analyze first row
The first row is {"ID", "Value"}, but the second row has a null in the first column.
Step 2: Understand PromoteAllScalars=false
This setting disallows promoting null or scalar values as headers.
Step 3: Cause of error
Null in data rows can cause header promotion to fail if PromoteAllScalars is false.
Final Answer:
The first row contains null values which cannot be promoted as headers. -> Option B
Quick Check:
Check for nulls in header row [OK]

Quick Trick: Nulls in header row cause promotion errors [OK]

Common Mistakes:

Assuming duplicates cause this error
Confusing PromoteAllScalars setting
Ignoring null values in headers

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You run this M code:

Step 1: Analyze first row

Step 2: Understand PromoteAllScalars=false

Step 3: Cause of error

Final Answer:

Quick Check:

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