I have a Spring Boot application in which the underlying tomcat regularly throws an error like this:

2024-06-11 11:12:40,529 ERROR [http-nio-9312-exec-5] <org.apache.juli.logging.DirectJDKLog>: Error processing request
java.io.UncheckedIOException: Cannot delete C:WindowsTemptomcat.9312.3138704811626004803workTomcatlocalhostROOTupload_f2043be0_7945_4211_b735_367546c4255b_00000000.tmp
    at org.apache.tomcat.util.http.fileupload.disk.DiskFileItem.delete(DiskFileItem.java:429)
    [...]
2024-06-11 11:12:40,536 ERROR [http-nio-9312-exec-5] <org.apache.juli.logging.DirectJDKLog>: Error reading request, ignored
java.io.UncheckedIOException: Cannot delete C:WindowsTemptomcat.9312.3138704811626004803workTomcatlocalhostROOTupload_f2043be0_7945_4211_b735_367546c4255b_00000000.tmp
    at org.apache.tomcat.util.http.fileupload.disk.DiskFileItem.delete(DiskFileItem.java:429)
    [...]
2024-06-11 11:12:40,537 ERROR [http-nio-9312-exec-5] <org.apache.juli.logging.DirectJDKLog>: Error running socket processor
java.io.UncheckedIOException: Cannot delete C:WindowsTemptomcat.9312.3138704811626004803workTomcatlocalhostROOTupload_f2043be0_7945_4211_b735_367546c4255b_00000000.tmp
    at org.apache.tomcat.util.http.fileupload.disk.DiskFileItem.delete(DiskFileItem.java:429)
    [...]

I have checked, and while the Folder C:WindowsTemptomcat.9312.3138704811626004803workTomcatlocalhostROOT exists, the file upload_f2043be0_7945_4211_b735_367546c4255b_00000000.tmp does not.

I have already tried setting spring.servlet.multipart.location to a less protected location, but the same error still occurred in that case. What’s more, in that case it resulted in files and folders that I could not even delete with administrator rights.

This happens when the following endpoint is called:

    @PostMapping(
        value = "/validate",
        consumes = MediaType.MULTIPART_FORM_DATA_VALUE,
        produces = MediaType.APPLICATION_JSON_VALUE
    )
    public ValidationResponse validateUploadedFile(
        @RequestParam("file") MultipartFile file
    ) {
        try {
            validator.validateMultipartFile(file);
            return ValidationResponse.buildValidResponse();
        } catch (ValidationFailedException e) {
            return ValidationResponse.buildValidationFailedResponse(e);
        } catch (Exception e) {
            return ValidationResponse.buildInvalidResponse(
                "Unexpected exception occurred while trying to validate file: <"
                    + e.getClass()
                    + "> "
                    + e.getMessage()
            );
        }
    }

The funny thing is that the request always passes, so whatever this exception is, it appears afterwards, and I have no idea what to do about it.

Does anyone have any suggestions? I am using Spring Boot Version 3.3.0