Error occurred while refreshing

[Asma-k]

Hi everyone, I'm fairly new to Power BI and I'm facing an issue with refreshing my dataset in Power BI Service. I've published my reports from Power BI Desktop, which are connected to a PostgreSQL database via ODBC using the connection string: driver={PostgreSQL Unicode(x64)};server=localhost;port=xxxx;database=database with Data cource name(DSN) as None. (But while trying to rempove the error below i did something that my powerbi desktop was also not fetchign the data, so changed the NONE option to dBASE Files. Now it is fetchign the data again) 

After publishing, I set up an on-premises data gateway, and in Power BI Service, the gateway appears online and the connection status shows as successful. However, when I click the refresh button in the Power BI Service, it takes a long time and then fails with the following error: "Data source error.

¨'The following system error occurred: Type mismatch. Table: memberships.'

I changed the data type of five columns in the memberships table from Date/Time to just Date. These changes are important for my calculations, so I can't change them back. Interestingly, the data still refreshes successfully in Power Query and in Power BI Desktop.

I also tried uploading a simplified version of the model with only raw data and no transformations, and that refreshes just fine in the Service. It seems like the issue may be related to the type change or how Power BI Service interprets it through the gateway. I would really appreciate any help or guidance in understanding what might be causing this "type mismatch" error and how I can fix it without reversing my column changes. Thanks in advance!

[lbendlin]

Have you considered using the native PostGres driver instead of ODBC?  

[Asma-k]

I am not able to use it. Only this driver works that i am currently using. 

[lbendlin]

What is the issue with the native driver?

[Asma-k]

The server does not support natic drivers. I am a beginner to this ETL process so I have been told to use ODBC. After your comment i treid to use the native driver but it has some connectivity issues witht the server. I am just connecting and fetching the data from that server. i have no control over it. 

[v-aatheeque]

Hi @Asma-k 

We haven’t heard back from you regarding our previous response and wanted to check if your issue has been resolved.

If it has, please consider clicking “Accept Answer” and “Yes” if you found the response helpful.
If you still have any questions or need further assistance, feel free to let us know — we're happy to help!

Thank you!

[v-aatheeque]

Hi @Asma-k 

We haven’t heard back from you regarding our previous response and wanted to check if your issue has been resolved.

If it has, please consider clicking “Accept Answer” and “Yes” if you found the response helpful.
If you still have any questions or need further assistance, feel free to let us know — we're happy to help!

Thank you!

[Asma-k]

I have not recieved any solution yet. the problem still exists.

[lbendlin]

Can you successfully create a System DSN in the ODBC 64 Bit control panel?

[Asma-k]

yes, it is successful.

[lbendlin]

Then use that DSN in your Power BI Desktop ODBC connection, instead of trying the DSN-less connection.

[Asma-k]

I tested to refersh the simple modle without any measures and calculations. It was successfully refreshing. 
Someone told me to see if the error is because you changed column types in memberships table. I checked in power query that maybe it is creating issue while loading from the source. But there was no issue, data was loading correctly. 

I have changed the column types in other tables as well, but they are loading perfectly. only this membership table is showing issues. 

[v-aatheeque · Accepted solution]

Hi @Asma-k 

If the Memberships table is the only one having problems despite similar changes being made to others tables, here are a few steps to investigate:

• Even if data loads fine in Power Query, ensure the type changes are compatible with the data model. For example, converting numeric columns to text might work in some contexts but could cause issues in calculations or relationships.
• If any calculated columns or measures rely on the Memberships table, they might break due to type changes or data format mismatches.
• After changing column types, ensure there are no invalid or unexpected values in the Memberships table that could trigger errors during refresh.

if the issue still persists request to raise a Support Ticket.

Hope it helps !
Regards,
v-aatheeque

If this post was helpful, please consider marking Accept as solution to assist other members in finding it more easily.

If you continue to face issues, feel free to reach out to us for further assistance!

[Asma-k]

There was one calculated column with the type:any which was suppose to be whole number. That column was creating the issue. 

[v-aatheeque]

Hi @Asma-k ,

We haven’t heard back from you regarding our previous response and wanted to check if your issue has been resolved.

If it has, please consider clicking “Accept Answer” and “Yes” if you found the response helpful.
If you still have any questions or need further assistance, feel free to let us know — we're happy to help!

Thank you!

[Asma-k]

It is still showing me this error 'Data source error: The following system error occurred: Type mismatch. Table: memberships'