Hello everyone,
  I'm trying to configure a new search topology, but when I want to activate it, I get this error:
  Set-SPEnterpriseSearchTopology -Identity $clone
  Set-SPEnterpriseSearchTopology : Rollback prending due to the last activation failure. Cannot start Activation of another topology now.
  At line:2 char:1
  + Set-SPEnterpriseSearchTopology -Identity $clone
  + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      + CategoryInfo          : InvalidData: (Microsoft.Offic...tSearchTopology:SetSearchTopology) [Set-SPEnterpriseSearchTopology], SearchTopologyActivationException
      + FullyQualifiedErrorId : Microsoft.Office.Server.Search.Cmdlet.SetSearchTopology

 I've tried to clear the cache, iis reset, rebooting,... but nothing works, I still get the error
 also, the timer job "Application Server Administration" is running from more than 1 day on 1 server, on the others it's running successfully.

SSA: Search Service Application

job-application-server-admin-service
-------------------------------------
Server1: job-application-server-admin-service recently ran 35 seconds ago
Server2: job-application-server-admin-service recently ran 36 seconds ago
WARNING: Server3: job-application-server-admin-service timer job does not appear to be running
Server4: job-application-server-admin-service recently ran 35 seconds ago
Server5: job-application-server-admin-service recently ran 36 seconds ago

Server6: job-application-server-admin-service recently ran 36 seconds ago
Server7: job-application-server-admin-service recently ran 31 seconds ago

Thanks in advance for your help

Try running the following command

Set-SPEnterpriseSearchQueryTopology -Active

instead of trying to activate the new clone.  Once you've gotten it to complete you can try again.

This is usually caused by some failure in creating an index partition.  If the command above fails then you can also try canceling the previous activation using the following.

$activating = Get-SPEnterpriseSearchTopology -Identity <Id of the activating topology> -SearchApplication $ssa
$activating.CancelTopologyActivation()

thanks for your answer but the first command doesn't work and the second one says "no activation in progress".

Then your only real choice may be to delete the entire Search service and recreate it from scratch.

if I don't have the choice... let's do it

Thanks

Can you verify the command you suggested here in this reply?

What do you mean by verify?  There is a linebreak in the command, so if you are trying to run it make sure that you are only trying to run two lines of code not three.  Other than that what are you asking?