Hi there

We have a problem with an important website - at least in the Backend of Umbraco 7.2.8 with saving and publishing.

Yesterday the users couldn't save and publish nodes anymore. If you click the button nothing happen and after a few seconds I got an error "undefined" (the red thingy). In the console of Chrome I get an additional error: umbraco/backoffice/UmbracoApi/Content/PostSave 504 Gateway Timeout (Timeout while reading response from Server).

But this error message makes no sense to me because everything else works. I can create DataTypes, save Templates and browse the website except creating or saving nodes (I didn't test medias yet).

What I tried to solve the problem:

• Check space on the server
• Check all logs (App_Data/Logs, Event Viewer and IIS Logs) nothing in there
• Save other things and check database
• CPU on Server (it's about 0%-2%)
• Restart App Pool: Actually that solved the problem but it occured today again

Here are some extra informations

• Site run about a year and a half without issues
• Umbraco 7.2.8
• Windows Server 2008 R2 with MSSQL 2008 R2 (not Express)
• umbraco.config is about 20MB
• Internal Examine Index has 18780 documents in index
• 22 GB free space (40 GB for C drive)

As I mentioned above after restarting the App Pool it works for some hours.

Do you have any idea how I can solve or track the problem?

Thank you
Calvin