Not able to attach iso - "is not a valid QCOW2"

[damien-kamerman]

Hi,

I'm not able to attach an iso to a KVM instance. The error is 'The downloaded file is not a valid QCOW2.'. It's definitely an iso and not a template so not sure why it's checking for QCOW2. I'm using version 4.20.1.0.

What could I be doing wrong? Has anyone seen this?

Here's the error from /var/log/cloudstack/agent/agent.log:
2025-08-26 10:55:02,985 ERROR [kvm.storage.KVMStorageProcessor] (AgentRequest-Handler-4:[]) (logid:) The downloaded file [/mnt/61e67fa7-f26a-34d1-bc20-553a1b6ff798/deaa3e8b-2fcf-443e-80a4-dca3309bfafa.iso] is not a valid QCOW2. java.lang.SecurityException: [/mnt/61e67fa7-f26a-34d1-bc20-553a1b6ff798/deaa3e8b-2fcf-443e-80a4-dca3309bfafa.iso] is not a valid QCOW2 because its first 4 bytes are not the QCOW magic string.
at org.apache.cloudstack.storage.formatinspector.Qcow2Inspector.validateQcowMagicString(Qcow2Inspector.java:172)
at org.apache.cloudstack.storage.formatinspector.Qcow2Inspector.validateQcow2HeaderFields(Qcow2Inspector.java:153)
at org.apache.cloudstack.storage.formatinspector.Qcow2Inspector.validateQcow2File(Qcow2Inspector.java:81)
at com.cloud.hypervisor.kvm.storage.KVMStorageProcessor.handleDownloadTemplateToPrimaryStorage(KVMStorageProcessor.java:2485)
at com.cloud.storage.resource.StorageSubsystemCommandHandlerBase.handleStorageCommands(StorageSubsystemCommandHandlerBase.java:81)
at com.cloud.hypervisor.kvm.resource.wrapper.LibvirtStorageSubSystemCommandWrapper.execute(LibvirtStorageSubSystemCommandWrapper.java:36)
at com.cloud.hypervisor.kvm.resource.wrapper.LibvirtStorageSubSystemCommandWrapper.execute(LibvirtStorageSubSystemCommandWrapper.java:30)
at com.cloud.hypervisor.kvm.resource.wrapper.LibvirtRequestWrapper.execute(LibvirtRequestWrapper.java:78)
at com.cloud.hypervisor.kvm.resource.LibvirtComputingResource.executeRequest(LibvirtComputingResource.java:1958)
at com.cloud.agent.Agent.processRequest(Agent.java:779)
at com.cloud.agent.Agent$AgentRequestHandler.doTask(Agent.java:1194)
at com.cloud.utils.nio.Task.call(Task.java:83)
at com.cloud.utils.nio.Task.call(Task.java:29)

Thanks,
Damien

[kiranchavala]

@damien-kamerman could you please let us know the output of the command

qemu-img info fiename.qcow2

root@ref-trl-9219-k-Mol8-kiran-chavala-kvm2 ~]# qemu-img info kvm.qcow2
image: kvm.qcow2
file format: qcow2
virtual size: 1 GiB (1073741824 bytes)
disk size: 196 KiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    compression type: zlib
    lazy refcounts: false
    refcount bits: 16
    corrupt: false
    extended l2: false

[damien-kamerman]

qemu-img info OracleLinux-R8-U9-x86_64-dvd.iso

image: OracleLinux-R8-U9-x86_64-dvd.iso
file format: raw
virtual size: 12.5 GiB (13434355712 bytes)
disk size: 12.5 GiB

[DaanHoogland]

not sure why this closed. @damien-kamerman , have you resolved your issue?

[damien-kamerman]

this is still an issue for me - not sure why it's closed

[weizhouapache]

re-opened

[weizhouapache]

@damien-kamerman
is the ISO direct-download ?

cc @kiranchavala , may worth test it

[damien-kamerman]

yes direct-download

[kiranchavala]

Thanks @damien-kamerman

@weizhouapache @DaanHoogland

Able to reproduce the issue

1. Register a iso as a direct download
2. Deploy a vm
3. Exception observed

2025-08-27 03:50:55,619 DEBUG [c.c.a.t.Request] (AgentManager-Handler-11:[]) (logid:) Seq 1-253046004062883746: Processing: { Ans: , MgmtId: 32987764753314, via: 1, Ver: v1, Flags: 10, [{"org.apache.cloudstack.agent.directdownload.DirectDownloadAnswer":{"retryOnOtherHosts":"true","result":"false","details":"The downloaded file is not a valid QCOW2. Ask the administrator to check the logs for more details.","wait":"0","bypassHostMaintenance":"false"}}] }

Logged a issue

#11521

[weizhouapache]

Fixed by #11532