Partial API Error in IntegrationHub ETL

[Varun M]

Hello,

I am working on Integrating Cisco Collector with ServiceNow via the IntegrationHub ETL. I have the REST API's for getting data from Cisco Collector, the Oauth app has been registered and also can successfully get the token.

The error I am seeing is when I open the ETL Transform Map that is supposed to pull in the data from the import sets. I constantly get the following error "There was an error with the partial preview API." and then subsequently step 2 which is "Prepare Source Data for Mapping" shows no data. I have not found any forums or documentation that is relevant to this error.

Would really appreciate your help on this.

Thanks!

[florian29]

@Per Kristian1 Hi that also works for me, thank you 🙂

[DaveHertel]

Thank you @Kristian1 Activating the transform also worked for me.  Error disappeared immedaitely after activating.

[Remus]

Root cause: A Reference field used in the lookup was configured to reference the wrong table. When the Partial Preview API attempted to perform the reference lookup, it was unable to fetch the target data, and the internal query object remained uninitialized. That led to the exception:

There was an error with the partial preview API. Transfomation failed: Cannot invoke "com.glide.db.meta.Query.addQuery(com.glide.util.IQueryCondition)" because "this.fQuery" is null

Fix: Correct the Reference field configuration (Dictionary entry) so the Reference points to the correct table.

[Remus]

Root cause: A Reference field used in the lookup was configured to reference the wrong table. When the Partial Preview API attempted to perform the reference lookup, it was unable to fetch the target data, and the internal query object remained uninitialized. That led to the exception:

There was an error with the partial preview API. Transformation failed: Cannot invoke "com.glide.db.meta.Query.addQuery(com.glide.util.IQueryCondition)" because "this.fQuery" is null

Fix: Correct the Reference field configuration (Dictionary entry) so the Reference points to the correct table.

[Akshay Choudha1]

Hello,

We ran into the exact same issue while integrating Cisco Collector with ServiceNow using IntegrationHub ETL.

Root Cause

The problem occurred after deploying the ETL configuration from one instance to another.

When moving ETL configurations via Update Sets, not all ETL-related records are consistently captured, especially if changes were made directly in the ETL (for example adding or removing fields in the transform). In our case, some related records under the Robust Transform Engine were missing in the target instance.

Because of that mismatch, the ETL Transform Map preview failed with:

"There was an error with the partial preview API."

And Step 2 – Prepare Source Data for Mapping – showed no data.

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What to Check

1. Open the Data Source from which the ETL is selected.

2. Open the Robust Transform.

3. Open the Transformer Definition.

4. In the Related List, check the Robust Transform Engine Entity records.

5. Compare the number of records between:

   • Source instance (where it works)

   • Target instance (where the error occurs)

In our case, the record counts were different between the two instances.

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Resolution

We manually recreated/synchronized the missing Robust Transform Engine Entity records in the target instance so that both instances matched.

After correcting the difference, the ETL Transform Map preview worked correctly and Step 2 populated the source data as expected.

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Important Note

In our experience, ServiceNow Update Sets do not always capture ETL changes completely, especially when modifying fields directly inside the ETL configuration (like adding/removing fields). These related Robust Transform Engine records can sometimes be missed.

If you encounter this partial preview API error after deployment, definitely compare the Robust Transform Engine Entity records between instances.

Hope this helps others facing the same issue!