We are currently updating our fleet of Ubuntu Core machines which includes updating snapd. As a safety precaution, we are also testing the downgrade of our machines. During automated testing, I sometimes run into this error when installing snapd:
Status Spawn Ready Summary
Done today at 07:21 UTC today at 07:23 UTC Ensure prerequisites for "snapd" are available
Undone today at 07:21 UTC today at 07:23 UTC Prepare snap "/var/lib/snapd/snaps/.local-install-2843541935" (15541)
Undone today at 07:21 UTC today at 07:23 UTC Run pre-refresh hook of "snapd" snap if present
Undone today at 07:21 UTC today at 07:23 UTC Stop snap "snapd" services
Undone today at 07:21 UTC today at 07:23 UTC Remove aliases for snap "snapd"
Error today at 07:21 UTC today at 07:23 UTC Make current revision for snap "snapd" unavailable
Undone today at 07:21 UTC today at 07:23 UTC Copy snap "snapd" data
Undone today at 07:21 UTC today at 07:23 UTC Setup snap "snapd" (15541) security profiles
Error today at 07:21 UTC today at 07:22 UTC Make snap "snapd" (15541) available to the system
Error today at 07:21 UTC today at 07:22 UTC Automatically connect eligible plugs and slots of snap "snapd"
Hold today at 07:21 UTC today at 07:22 UTC Set automatic aliases for snap "snapd"
Hold today at 07:21 UTC today at 07:22 UTC Setup snap "snapd" aliases
Hold today at 07:21 UTC today at 07:22 UTC Update managed boot config assets from "snapd" (15541)
Hold today at 07:21 UTC today at 07:22 UTC Run post-refresh hook of "snapd" snap if present
Hold today at 07:21 UTC today at 07:22 UTC Start snap "snapd" (15541) services
Hold today at 07:21 UTC today at 07:22 UTC Clean up "snapd" (15541) install
Hold today at 07:21 UTC today at 07:22 UTC Run health check of "snapd" snap
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Make current revision for snap "snapd" unavailable
2025-06-30T07:23:08Z ERROR "usr-lib-snapd.mount" failed to stop: timeout
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Make snap "snapd" (15541) available to the system
2025-06-30T07:21:54Z INFO Requested daemon restart (snapd snap).
2025-06-30T07:22:59Z ERROR "usr-lib-snapd.mount" failed to stop: timeout
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Automatically connect eligible plugs and slots of snap "snapd"
2025-06-30T07:21:54Z INFO Waiting for automatic snapd restart...
2025-06-30T07:22:51Z ERROR "usr-lib-snapd.mount" failed to stop: timeout
When I try to install the revision again, it works without problem. Do you know what is going on?
It should be noted that my automated test installs snapd revision 24724 approximately 5 minutes before attempting to install snapd revision 15541.