Looks like you are running umbraco on azure, how your indexes is defined ? TempEnvDirectoryFactory or SyncTempEnvDirectoryFactory . In message before second rebuild you can see what umbrco think what is new server, I think what is TEMP\DistCache is empty or removed

Hi Yakov - thanks for your reply.

We are indeed running on Azure and we're using SyncTempEnvDirectoryFactory. Is there a reason Umbraco would think it's a new server between the two cache rebuilds?

Let's verify what you have all setting on azure

https://our.umbraco.com/documentation/getting-started/setup/server-setup/azure-web-apps

<add
    key="Umbraco.Core.MainDom.Lock"
    value="SqlMainDomLock" />
<add
    key="Umbraco.Core.LocalTempStorage"
    value="EnvironmentTemp" />
<add
    key="Umbraco.Examine.LuceneDirectoryFactory"
    value="Examine.LuceneEngine.Directories.SyncTempEnvDirectoryFactory, Examine" />

I also defined WEBSITEDISABLEOVERLAPPED_RECYCLING=1 on azure settings

for front servers I believe

https://our.umbraco.com/Documentation/Getting-Started/Setup/Server-Setup/Load-Balancing/azure-web-apps

Hi Yakov

We have those three keys set correctly.

We don't have WEBSITEDISABLEOVERLAPPED_RECYCLING as your second link suggests that it is only required for v8.6.0 - v8.6.3 (and we are on v8.8.0). Is that not correct?

WEBSITEDISABLEOVERLAPPED_RECYCLING - generally is not need by documentation but we set it any case.

today I have no umbraco in 8.8 version on azure to check it, what is situation ins sql server may be it reach maximum of DTU and stop answer?

By the way fo you have one front or more?

I remember what this fix is also affect s it https://github.com/umbraco/Umbraco-CMS/pull/9543

Interesting - the documentation says that up to 8.6.3 WEBSITEDISABLEOVERLAPPED_RECYCLING was needed for Replica apps only (and Master apps would need the Umbraco.Core.MainDom.Lock). Then in 8.6.4 onwards Umbraco.Core.MainDom.Lock would cover both Master and Replicas. Do you set it on your Master/Replicas/both?

I don't believe there is a DTU issue but will double check.

We have two front-end web apps in addition to the master app.

I was aware of the fix you've linked as we've also had an intermittent issue with lock timeout requests. It is not yet patched for 8.8 but it sounds promising and I may look into upgrading to 8.10.1.

if you have more than one front you should define TempEnvDirectoryFactory to prevent locks

<add key="Umbraco.Examine.LuceneDirectoryFactory" value="Examine.LuceneEngine.Directories.TempEnvDirectoryFactory, Examine" />

Would that be on all three apps or just the two front-ends?

Generally only on loadbalanced apps, but you can define on master too

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