HttpException 503 The server is currently unavailable


We’re using RaiDrive to connect over SSL to our QNAP over WebDAV. We find RaiDrive very usefull software. Thanks!

For one user (on Windows 10) however, the connection seems to stop frequently, so she can’t save edited documents, move or delete files. In the log it says:

FOLDER ENUM : API Call Error : {“WinErrorCode”:1237,“NotifyErrorCode”:401,“RaiException”:“WebDAV List : {foldername} : Failed”,“Filename”:{foldername}",“WebResponseCode”:503,“HttpException”:“503 The server is currently unavailable”,“HttpReferenceMessage”:""}

So where the error formatting seems to expect a filename, the folder name is shown again. I’m not sure if that is relevant.

Other users with a similar setup don’t experience these problems. What could be the problem? And more importantly: how to solve it?

Thanks for your help!

1 Like

Hi~ @Ruben,

We need to analyze the action flow relative with this issue.
Could you send whole log files to


Thanks for the reply. I was expecting a notification in my mailbox when you had replied, but I didn’t receive anything. Hence my late reaction.

I’ve just sent you the log file.

Thanks for your help!

We’ve just looked around the log files you sent.
It’s a little bit weird and seems to be caused by some fundamentals.
Could you check the QNAP firmware version?

Our QNAP is on firmware version 4.2.6 Build 20200109, which is the most recent one for this model (TS-239 Pro II).

After reading quite a lot of 503 problems on the QNAP forum, my impression is they all had permanent troubles logging in to the main web interface or to a particular service. Funny thing with us is, we can reach the WebDav service. For some users it’s usualy fine, for others it takes several tries. And some can reach WebDav fine, but seem to have a problem keeping the connection alive. But never is it really permanently “dead”, like the cases in the QNAP forum.
And we never have any trouble reaching the main webinterface.

I hope you can think of a cause for this quirky behavior because I’m stumped.

Kind regards,