What causes Fabric Copy Activity Error 20551?

The dataset was created without specifying a file format (e.g., CSV, JSON, Parquet, Avro) or the format block was left empty. A dataset was cloned or migrated from another environment and the format settings were not carried over correctly. The format settings were manually removed or corrupted in the dataset JSON definition. Using a generic or template dataset that requires format properties to be filled in before use

How do I fix Fabric Copy Activity Error 20551?

Step 1: Open the dataset associated with the failing Copy Activity in Fabric Data Factory and navigate to the 'Format' or 'Connection' tab to review the current format settings.. Step 2: Identify the file format of your source or destination data (e.g., DelimitedText/CSV, JSON, Parquet, Avro, ORC, Binary) and select it from the format type dropdown.. Step 3: Configure all required format-specific properties such as column delimiter, row delimiter, compression type, encoding, and header row settings as appropriate for your file type.. Step 4: Save the dataset and return to the Copy Activity to verify that both source and sink datasets now show complete format configurations.. Step 5: Perform a debug or preview run of the Copy Activity to confirm the format settings are valid and data can be read or written correctly.

Medium severityconfigurationMicrosoft Fabric →

Power BI Refresh Error:
Fabric Copy Activity Error 20551

What does this error mean?

The Copy Activity dataset is missing required format settings, preventing Fabric from correctly reading or writing the data file. The activity will fail until the appropriate format configuration is provided.

Common causes

1The dataset was created without specifying a file format (e.g., CSV, JSON, Parquet, Avro) or the format block was left empty
2A dataset was cloned or migrated from another environment and the format settings were not carried over correctly
3The format settings were manually removed or corrupted in the dataset JSON definition
4Using a generic or template dataset that requires format properties to be filled in before use

How to fix it

1Step 1: Open the dataset associated with the failing Copy Activity in Fabric Data Factory and navigate to the 'Format' or 'Connection' tab to review the current format settings.
2Step 2: Identify the file format of your source or destination data (e.g., DelimitedText/CSV, JSON, Parquet, Avro, ORC, Binary) and select it from the format type dropdown.
3Step 3: Configure all required format-specific properties such as column delimiter, row delimiter, compression type, encoding, and header row settings as appropriate for your file type.
4Step 4: Save the dataset and return to the Copy Activity to verify that both source and sink datasets now show complete format configurations.
5Step 5: Perform a debug or preview run of the Copy Activity to confirm the format settings are valid and data can be read or written correctly.

Frequently asked questions

Does this error affect both the source and sink datasets, or only one?

It can affect either the source dataset, the sink dataset, or both. The error message context will typically indicate which dataset is missing format settings. Check both datasets in your Copy Activity if the initial fix does not resolve the error.

If my data is binary or I don't know the format in advance, what format setting should I use?

Fabric Data Factory provides a 'Binary' format type for scenarios where you want to copy files as-is without parsing their contents. This is useful for file transfer use cases. For unknown structured formats, use the 'DelimitedText' type as a starting point and adjust the delimiter and other properties based on your actual file structure.