Is not a valid M connection string

[panjahr]

We have an Excel workbook that we import to the Power BI Service and schedule a refresh.

The workbook refreshes fine manually on desktop, but manual/scheduled refresh on Power BI Service has broken at some point (it has worked). We have tried both personal and enterprise gateways. The gateway on Power BI says ready to go. The gateway log though has warnings for all 5 datasources:

"is not a valid M connection string".

Our datasources are:

- 4 Web resources

- 1 PostgreSQL database on Heroku

The 4 web resources seem to work on the personal gateway.

We have no clue how to debug this further. Can anyone help?

[panjahr]

We have an Excel workbook that we import to the Power BI Service and schedule a refresh.

The workbook refreshes fine manually on desktop, but manual/scheduled refresh on Power BI Service has broken at some point (it has worked). We have tried both personal and enterprise gateways. The gateway on Power BI says ready to go. The gateway log though has warnings for all 5 datasources:

"is not a valid M connection string".

Our datasources are:

- 4 Web resources

- 1 PostgreSQL database on Heroku

The 4 web resources seem to work on the personal gateway.

We have no clue how to debug this further. Can anyone help?

[v-qiuyu-msft]

Hi @panjahr,

From your description, it seems the dataset can be refreshed successfully before, right? 

Did you modify the Power BI service report during this period? Please try to update gateways to the latest version then refresh again. 

Best Regards,
Qiuyun Yu 

[panjahr]

Hi Quiyun,

Thanks for your quick reply!

I think I've narrowed it down to the data sources and my gateway. Way to reproduce issue:

1. I go to Power BI service and click Manage gateways

2. I click Test all connections

3. My On-premises data gateway log now has warnings with "Is not a valid M connection string" for each data source.

I don't expect the dataset queries to play any role in the above scenario. It must simply be the data sources and my gateway, right? If this is true, I really have a hard time figuring out what is wrong as we haven't made any changes to the data sources for a very long time! It must be (Windows) updates on the gateway computer, or the update of the gateway which have broken something.

Please help.

I have updated the gateway to: 14.16.6584.1.