xperf refusing to load any symbol - windows

Question

With these command lines:
set _NT_SYMBOL_PATH=srv*C:\symbols*http://msdl.microsoft.com/downloads/symbols
XPerf -on FILE_IO
XPerf -d trace.etl
XPerf -symbols verbose -i trace.etl > output.csv
I get the following output:
XPerf: warning: applying restriction of access for trace processing
xperf: Using symbol path: srv*C:\symbols*http://msdl.microsoft.com/downloads/symbols
xperf: Using executable path: srv*C:\symbols*http://msdl.microsoft.com/downloads/symbols
xperf: Using SymCache path: \SymCache
xperf: SymCache engine version: v1.1
xperf: Minimum accepted SymCache version: v1.1
xperf: Minimum accepted SymCache version: v1.1
[1/2] 100.0%
[2/2] 100.0%
Warning: This trace does not contain the information needed to perform proper symbol decoding.
It was most likely stopped improperly. Please consult the documentation for information on how
to stop trace sessions (for example XPerf -stop <logger names> -d <merged.etl>)
If you still have access to the machine on which this trace was collected, you can have XPerf
add the required symbol information by running the following on that machine:
XPerf -merge <trace1.etl> <trace2.etl> ... <merged.etl>
Running this command on any machine other than the one on which the trace was collected will
result in incorrect symbol decoding.
What am I doing wrong?

Answer 1

XPerf -merge trace.etl trace_with_correct_symbol_decoding_info.etl
Now you can parse trace_with_correct_symbol_decoding_info.etl with your original command:
XPerf -symbols verbose -i trace_with_correct_symbol_decoding_info.etl > output.csv
The merge command not only merges multiple etl files, it also "adds image identification information required for safe symbol decoding."
D:\>xperf -help merge
Trace merge options:
xperf -merge trace1.etl trace2.etl ... merged.etl
-Merge trace1.etl trace2.etl ... merged.etl Merge trace1.etl trace2.etl ... into
merged.etl, also adding image identification
information required for safe symbol
decoding.