For some reason, bug 1366140 caused Talos xperf to access msctf.dll when it previously had not. But oddly, the failures only appear to have happened on Beta (ESR52 *could* also be affected, but we don't run Talos on it, so who knows). https://treeherder.mozilla.org/logviewer.html#?job_id=102459080&repo=mozilla-beta After discussion with Joel, we decided it was best to whitelist it for now, but we should probably at least have some understanding of what happened before completely forgetting about it (not to mention deciding if something needs to be done on m-c or not still).
I don't understand what the error means, though. On the other hand, IIUC, msctf.dll may be accessed by a lot of programs including TSF and active keyboard layout's DLL (note that they are in our main process). We may have changed lifetime of some COM objects of TSF module in some cases. Therefore, it could change TSF and active keyboard layout behavior only in specific case. The difference between Beta and Nightly could occur. Application name of Firefox Beta and Nightly is different. Some code in TSF module or IME *might* check it for avoiding our unexpected behavior or something.
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