problem starting power bi desktop :

Hi Guerrero 

Below can be the reasons for the error:

• check if .NET framework is properly installed on your machine(try uninstall and reinstall again)
• Power BI desktop may not be properly installed(try uninstall and reinstall again).
• Check if you have access permissions on the drive where PBI desktop is installed.

Please refer below link for more information:

https://www.microsoft.com/en-us/download/details.aspx?id=58494 

Please give kudos or mark it as solution once confirmed.

Thanks and Regards,

Praful

Hi Guerrero 

This error “Object reference not set to an instance of an object” means Power BI Desktop is trying to access something (like a cache, credential, or visual) that is not initialized correctly.
It often happens when local workspace or configuration files are corrupted.

Try these steps in order:

1. Reset Power BI local workspaces
Close Power BI Desktop and delete these folders:

%LOCALAPPDATA%\Microsoft\Power BI Desktop\AnalysisServicesWorkspaces
%LOCALAPPDATA%\Microsoft\Power BI Desktop Store App\AnalysisServicesWorkspaces

Then reopen Power BI Desktop.

2. Clear cached credentials
In Power BI Desktop go to File > Options and settings > Data source settings,
select Clear Permissions for all data sources, and restart Power BI.

3. Disable custom visuals or preview features
Go to File > Options > Preview features and uncheck all non-essential options.
Restart Power BI.

4. Reinstall Power BI Desktop
If the issue continues:

5. Uninstall Power BI Desktop completely.

Delete the folder:

%AppData%\Microsoft\Power BI Desktop

6.Check graphics drivers
Outdated GPU drivers can sometimes cause startup failures.
Update your graphics card drivers to the latest version.

If the problem still occurs after all these steps, open a support ticket with Microsoft Power BI Support .

https://support.fabric.microsoft.com/

If this post helps, then please consider Accepting it as the solution to help the other members find it more quickly