Hello I would like to know 3 points about the following errors.

『Couldn't delete file : file://web:/StaticContent/global/ServiceExport/XXXXXX.pdf [ WebContainer : 16] [TABTHREAD1] [ ] [ REM:01.01.01] ( generated.pega_rules_uti』

Such errors are This happens when a user opens multiple cases and uploads a file, what are the conditions under which a PDF is stored in ServiceExport of the AP server?

(1) What are the conditions under which the PDF is stored in ServiceExport of the AP server? Also, is it only PDFs that are stored in ServiceExport, or is it not Excel, etc.? (2) What operation of the user causes this error? (3) Does the user operation screen show any error messages, etc.?

Pega Version: 7.4　

Best regards