KBI0027: “Transfer already in progress, or unable to take transfer lock”#
Adina Wagner <email@example.com>
transfer lock, datalad get, data retrieval
When retrieving or uploading data, users can in rare cases see a failure together with the message
Transfer already in progress, or unable to take transfer lock.
This message originates in lock files git-annex uses to keep several transfer processes from interfering with each other.
Usually, it should suffice to wait a bit until the process that holds the lock open exits and releases the lock automatically.
But in some cases, e.g. when CTRL-C’ing a process unluckily or on Windows, the lock file can get stale, and the error message remains regardless of how long one waits.
When this happens, do the following:
Be sure that there is no git-annex process that holds the lock open for a good reason. You should check the processes running on your system, and - when transferring data to a remote system - also the processes over there.
If you are sure that the lock is stale, remove the files inside of
.git/annex/transfer/, and retry.
A short discussion for further reading can be found here.