update error after install - locking problem

[FrankP]

E: Kon vergrendeling /var/lib/dpkg/lock-frontend niet verkrijgen. Proces 3917 houdt deze grendel vast (apt-get)
E: Kan de vergrendeling voor het dpkg-frontend (/var/lib/dpkg/lock-frontend) niet verkrijgen. Gebruikt een ander proces dit?

Any solution?
Thanks,

Frank

PS Later, after trying the update gain, it said update was complete. But I do not know if that is true...

[stevef]

Any software update process (like a manual update, a background update or running a package manager) requires exclusive access to update resources and will lock them while running to prevent another update process starting.  If one update process has locked the resources and a second one tries to start, the second will not be able to get the resource and will generate a message like this.

Usually all that is needed is to wait until the first process completes and releases the resource.  If the second attempt to update/upgrade worked then all is well.

If the problem did not self-resolve it is possible that something (like an interrupted update) may have broken the mechanism and more investigation would have been required to clear the lock.