topic Re: Using "Load to Tables" function on a file in a lakehouse does not seem to work on subsequent loads in Data Engineering

Using "Load to Tables" function on a file in a lakehouse does not seem to work on subsequent loads

anon97242 — Wed, 06 Aug 2025 19:25:19 GMT

Hello,

Encountering an issue with writing to an existing table in a lakehouse using "Load to Tables" function for Files (csv) uploaded to lakehouse:

It seems that if you use this function then rename the table, and then attempt to load to it again the data never loads. I do see some parquet files in the "Undefined" folder of the lakehouse.

If I proceed to delete the destination table then a new table appears, where the name does not match what was uploaded, that is loaded with the data.

It would be great if this worked for existing tables better.

Re: Using "Load to Tables" function on a file in a lakehouse does not seem to work on subsequent loads

v-pnaroju-msft — Thu, 07 Aug 2025 16:03:24 GMT

Hi anon97242,

We sincerely appreciate your inquiry submitted through the Microsoft Fabric Community Forum.

Based on my understanding, when a CSV file is initially loaded via the Load to Tables → New Table option, Fabric creates a table and registers it within its internal metadata. However, if the table is subsequently renamed through the user interface, the original reference used by the Load to Tables function is not updated. This leads to the system losing association with the renamed table, resulting in files being written to the Undefined/Unidentified folder. This constitutes a limitation in the current system.

Please follow the steps outlined below, which may help to resolve the issue:

Delete the renamed table if it is no longer usable. Reload the CSV file using the Load to Tables → New Table option. Kindly avoid renaming this table after creation. For all future data loads into this table, use the Load to Tables → Existing Table option. Renaming a table after the initial load breaks the internal mapping, causing subsequent load operations to fail.
If renaming tables is essential for better readability, please consider using the SQL endpoint to create a view with the preferred name. While preserving the original technical table name, apply naming clarity at the Power BI dataset level.

Furthermore, you may also submit your valuable feedback to improve this behavior on the Microsoft Fabric Ideas portal via the following link: Fabric Ideas - Microsoft Fabric Community

We hope that the above information will assist you in resolving the issue. Should you have any further queries, please feel free to reach out to the Microsoft Fabric community.

Thank you.

Re: Using "Load to Tables" function on a file in a lakehouse does not seem to work on subsequent loads

v-pnaroju-msft — Sun, 10 Aug 2025 15:07:09 GMT

Hi anon97242,

We would like to follow up and see whether the details we shared have resolved your problem.
If you need any more assistance, please feel free to connect with the Microsoft Fabric community.

Thank you.

Re: Using "Load to Tables" function on a file in a lakehouse does not seem to work on subsequent loads

v-pnaroju-msft — Wed, 13 Aug 2025 15:50:37 GMT

Hi anon97242,

We are following up to see if what we shared solved your issue. If you need more support, please reach out to the Microsoft Fabric community.

Thank you.

Re: Using "Load to Tables" function on a file in a lakehouse does not seem to work on subsequent loads

apturlov — Wed, 13 Aug 2025 16:31:40 GMT

anon97242 I have tested that the proposed solution descibed above by v-pnaroju-msft does work. The data file can be loaded into existing table in overwrite or append mode and the load will be successful.

Re: Using "Load to Tables" function on a file in a lakehouse does not seem to work on subsequent loads

v-pnaroju-msft — Sat, 16 Aug 2025 19:52:38 GMT

Hi anon97242,

We wanted to see if the information we gave helped fix your problem. If you need more help, please feel free to contact the Microsoft Fabric community.

Thank you.

Re: Using "Load to Tables" function on a file in a lakehouse does not seem to work on subsequent loads

anon97242 — Mon, 18 Aug 2025 14:51:36 GMT

Thanks for indicating this is a current limitation v-pnaroju-msft .

Unfortunate that it ignores the defined destination table, hopefully this is addressed in a future release.