When trying to export a report to Excel and user receives an error stating : Unable to create the store directory. (Exception from HRESULT: 0x80131468)

The error is likely seen when trying to export a large amount of data.

Example:

Detailed GL Cross-Tabbed Report w/References 
Date Range from 05/01/2019 to 06/01/2019 
Blank - All Accounts

However if you were to run these parameters, with a smaller date range it would then work.

Detailed GL Cross-Tabbed Report w/References 
Date Range from 05/01/2019 to 05/15/2019 
Blank - All Accounts

Try changing the below setting in the IIS App Pool.