When starting the QEMU driver we load all domain XMLs. This means, that post parse callbacks are run for each XML, but they are allowed to fail because we will run them again when starting a domain. In the case I am fixing, we were unable to look up QEMU capabilities (in both post parse runs) and reported appropriate error, sort of. It can be found in the logs, but the caller doesn't get it because after 5331c4804f4 it is reset. Therefore, as reported here [1], if we are unable to start QEMU for caps probing the following will happen: virsh start fedora error: Failed to start domain fedora error: An error occurred, but the cause is unknown 1: https://www.redhat.com/archives/libvir-list/2020-July/msg00673.html Fixes: 5331c4804f4 Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_domain.c | 1 - 1 file changed, 1 deletion(-) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index c365d92ae0..f31690c50a 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -5307,7 +5307,6 @@ qemuDomainPostParseDataAlloc(const virDomainDef *def, if (!(*parseOpaque = virQEMUCapsCacheLookup(driver->qemuCapsCache, def->emulator))) { - virResetLastError(); return 1; } -- 2.26.2