Hi @EMILIOCOLINA ,
If I understand correctly, it seems that got failed when you connect to SQL Server. The following threads are the ones which has the similar problem as yours, hope their solution can help you solve the problem.
Uncheck "Encrypt Connections" option
sql server - Login Error while connecting SQL Database through Power BI? - Database Administrators S...
By default, the Encrypt connection check box is selected to signify that Power BI Desktop connects to database using an encrypted connection. If a connection to your SQL Server is not established using an encrypted connection, that Power BI Desktop prompts to connect using an unencrypted connection.
Once you click OK, it will be directly prompted to turn off encryption. Or you can go to
File->Options and Settings -> Data Source Settings, choose your SQL Server data source and select Edit and uncheck "Encrypt Connections" option.
In addition, when we connect to SQL Server in Power BI Desktop, need to select the authentication mode to connect to the SQL Server database.
1) Windows: This is the default selection. Select this if you want to connect using Windows authentication.
2) Database: Select this if you want to connect using SQL Server authentication. After you select this, specify a user name and password to connect to your SQL Server instance.
Note: I know it's foolish and so simple but works for me anyway @sepupic Thanks for useful comment.
Solved: A connection was successfully established...error ... - Microsoft Fabric Community
The values in the thumbprint of the certificate in "Protocols for MSSQLSERVER" of SQL Server Network Configuration must be the same that appears in the registry in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL10.<INSTANCENAME>{=html}\MSSQLServer\SuperSocketNetLib in the Certificate value.
Solved: "Microsoft SQL: connection successfully establish... - Power Platform Community
Best Regards
