The "current transaction is aborted, commands ignored until end of transaction block" message usually occurs when there is an error in the code that is being executed within a database transaction. When this error occurs, the current transaction is rolled back, and any subsequent commands are ignored until the end of the transaction block.

There are several reasons why this error may occur when trying to import a file in Odoo 15:

1. Data Integrity: The data in the excel file may not match the expected format or contain invalid values that are causing the import to fail.

2. Missing fields: The excel file may be missing some required fields that are necessary for the import.

3. Model not found: The code may be trying to import data into a model that doesn't exist in the system.

4. Permission issues: The user may not have the proper permissions to import data into the specified model.

5. Syntax errors: There may be syntax errors in the code that is responsible for importing the data, causing the transaction to fail.

You should check your code and the excel file to see if any of these issues are present. Also, you can check the log in the odoo server to see the more details about the error to help you to fix it.

It might be helpful to share some of your code and the excel file, so that we can take a closer look and provide more specific guidance.