ADF Oracle V2 Linked Service – “Failed to import source schema. Cannot read properties of undefined (reading 'toLowerCase')

Question

ADF Oracle V2 Linked Service – “Failed to import source schema. Cannot read properties of undefined (reading 'toLowerCase')

I’m facing an issue in Azure Data Factory when using an Oracle V2 linked service. When I try to import the source schema in the Copy Activity mapping tab, I receive the following error:

"Failed to import source schema. Cannot read properties of undefined (reading 'toLowerCase')"

However, the Preview Data feature works correctly with the same dataset and linked service, so the connection itself seems fine.

Additional notes:

This issue occurs only with Oracle V2 linked services.
Other linked services (e.g., SQL Server, Azure SQL, etc.) do not show this problem.
The Oracle driver and credentials are valid, and the test connection succeeds.

Has anyone encountered this error before, or is this a known issue with Oracle V2 in ADF? Any guidance or workaround would be appreciated.

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Pilladi Padma Sai Manisha 4,905 Reputation points Microsoft External Staff Moderator

2026-02-19T16:44:38.53+00:00
Hi Mohamed Youssef Ehab Ahmed Ghanem,
Thankyou for reaching microsoft Q&A!
Oracle V2 requires the latest Self-Hosted Integration Runtime (SHIR) to work correctly. Please upgrade your SHIR to the latest version, as older versions may cause unexpected failures.

Additionally, this is a known behavior with the Oracle V2 connector due to stricter Parquet data type handling. To ensure compatibility with legacy Oracle data types, please enable backward compatibility by adding the following property in the Oracle linked service under typeProperties:

"supportV1DataTypes": true

After upgrading SHIR and enabling this setting, retry the copy activity. This should resolve the issue.

Please let us know if the issue persists or if you need help with the configuration.
Juan Harrington 0 Reputation points

2026-02-19T20:50:11.41+00:00

I am having the same issue and it only started to occur a couple days ago. Prior I was able to create copy activities and use the import mapping fine. Now if I go to any existing activity or new copy activities and try I get the same error. We are on the latest SHIR v 5.58.9395.1 and I added the "supportV1DataTypes": true to the linked connector. Did something change recently since it was working?
Saraswathi Devadula 14,400 Reputation points Microsoft External Staff Moderator

2026-02-20T12:32:00.6166667+00:00

Hi Mohamed Youssef Ehab Ahmed Ghanem,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

1 answer

Your answer

Pilladi Padma Sai Manisha 4,905 Reputation points Microsoft External Staff Moderator

2026-02-19T16:44:38.53+00:00

Hi Mohamed Youssef Ehab Ahmed Ghanem,
Thankyou for reaching microsoft Q&A!
Oracle V2 requires the latest Self-Hosted Integration Runtime (SHIR) to work correctly. Please upgrade your SHIR to the latest version, as older versions may cause unexpected failures.

Additionally, this is a known behavior with the Oracle V2 connector due to stricter Parquet data type handling. To ensure compatibility with legacy Oracle data types, please enable backward compatibility by adding the following property in the Oracle linked service under typeProperties:

"supportV1DataTypes": true

After upgrading SHIR and enabling this setting, retry the copy activity. This should resolve the issue.

Please let us know if the issue persists or if you need help with the configuration.
Juan Harrington 0 Reputation points

2026-02-19T20:50:11.41+00:00

I am having the same issue and it only started to occur a couple days ago. Prior I was able to create copy activities and use the import mapping fine. Now if I go to any existing activity or new copy activities and try I get the same error. We are on the latest SHIR v 5.58.9395.1 and I added the "supportV1DataTypes": true to the linked connector. Did something change recently since it was working?
Saraswathi Devadula 14,400 Reputation points Microsoft External Staff Moderator

2026-02-20T12:32:00.6166667+00:00

Hi Mohamed Youssef Ehab Ahmed Ghanem,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

Answer 1

Hi ,

Thanks for reaching out to Microsoft Q&A.

Yes, this is a known quirk with the Oracle V2 connector in adf when the metadata returned by Oracle does not fully match what ADF expects. Preview works because it only runs the query, but schema import fails when column metadata (for example mixed-case names, synonyms, unsupported data types, or empty column aliases) is returned as null, which triggers the toLowerCase error in the UI.

Typical workarounds are to avoid auto import and define mappings manually, use a custom query with explicit column aliases in upper case, or create a view in Oracle and point adf to that view instead of the base object. If possible, also check that you are on the latest Oracle client/ODBC version and try switching to query mode rather than table mode, as that often bypasses the metadata bug.

Please 'Upvote'(Thumbs-up) and 'Accept' as answer if the reply was helpful. This will be benefitting other community members who face the same issue.

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ADF Oracle V2 Linked Service – “Failed to import source schema. Cannot read properties of undefined (reading 'toLowerCase')

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