Investigating intermittent JSON errors

[RD1965]

Hi,

I have several reports that all retrieve data from a SQLPostgre DB via an ODATA connection to a https website.

Intermittently a few of the reports will fail to refresh with JSON errors - rerun then they will be fine.

E.G. 

[0] -1055784934: DataSource.Error: OData: Invalid JSON. Unexpected end of input reached while processing a JSON string value.. DataSourceKind = OData. DataSourcePath = https://xxx/datahub/xxx/odata/Device . The exception was raised by the IDataReader interface. Please review the error message and provider documentation for further information and corrective action.

What I'd like to do is investigate this to reduce/remove occurances.

Does Power BI Report Server or SSMS have any features or tools to investigate?

Thanks

[v-hashadapu · Accepted solution]

Hi @RD1965 , Thank you for reaching out to the Microsoft Community Forum.

This error almost always means that Power BI is receiving a truncated or incomplete JSON payload from the OData service before the response finishes. This isn’t a Power BI bug, it’s a transport or service layer problem between the OData endpoint and Power BI.

When Power BI refreshes, it sends multiple parallel requests to the OData feed. If the web service, gateway or network drops a connection mid-stream or if the backend API times out or runs out of memory, the JSON response can end abruptly. Power BI then fails the refresh with the message you see. The fact that re-running works fine fits this pattern, the underlying data is valid, but the response occasionally dies in transit.

To confirm this, start by enabling diagnostic tracing in Power BI Desktop or checking the Report Server trace logs. They’ll show the exact OData request and whether the response was closed prematurely. If you test the same OData URL in a browser or with Invoke-WebRequest and sometimes get incomplete JSON, the fault is definitely at the OData or network level. On the server side, review your web/API logs and PostgreSQL slow query logs for aborted requests or serialization timeouts.

Once verified, mitigation options are to reduce concurrency (disable parallel table loading in Power BI), paginate or trim large OData queries, increase timeouts in your API or proxy and if possible, connect directly to PostgreSQL using the native connector instead of OData. That avoids JSON serialization entirely and is the Microsoft-preferred method for reliability.

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