Free Busy - Troubleshooting

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Free/Busy Troubleshooting

   KB 22346        Last updated on 2019-05-27  

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Explain Free/Busy Troubleshooting in detail.


When requesting free/busy data, the code translates the request using the domain within the zimbraPublicServiceHostname. The domain within zimbraPublicServiceHostname must be reachable. If not, the request will timeout, and there is no data for the requester.

The ZCS server uses the zimbraMailTransport setting and fbqueue folder to obtain the Free/Busy data for an internal user. A successful lookup will write the following into the access.log -  -  [10/Sep/2015:17:29:31 +0000] "GET /service/pubcal/freebusy.ifb? HTTP/1.0" 200 - "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:40.0) Gecko/20100101 Firefox/40.0" 411

If there is an issue with zimbraMailTransport or fbqueue, the following error will occur within the mailbox.log on the server of the user making the request:

2015-07-23 13:11:34,082 ERROR [qtp509886383-85:https://10.999.99.99:8443/service/pubcal/freebusy.ifb?] [] fb - can't find free/busy provider for user

If this issue occurs, you will need to set the zimbraMailTransport setting for the user:

zmprov ga zimbraMailTransport

You also need to ensure that the zimbra user owns the fbqueue folder and has read and write access to the folder.


In the case where both accounts reside on different servers, you must ensure that the system can send requests to each server. If port 8443/443 or 8080/80 is inaccessible, then the attempt will also fail.

Each account can limit access to their personal Free/Busy data.

zmprov ga zimbraACE
  • Don't let anyone see my free/busy information
    zimbraACE: 00000000-0000-0000-0000-000000000000 all -viewFreeBusy
  • Allow only users of my domain to see my free/busy information
    zimbraACE: 7152f996-c550-400b-8090-500c3dab3272 dom viewFreeBusy
  • Allow only users of internal domains to see my free/busy information
    zimbraACE: 00000000-0000-0000-0000-000000000000 all viewFreeBusy
  • Allow only the following internal users to see my free/busy information
    zimbraACE: e7d68c77-6aad-4683-a845-74e64378faf6 usr viewFreeBusy
  • The configuration is treated as "Allow both internal and external users to see my free/busy information" if it is NULL or the following:
    zimbraACE: 99999999-9999-9999-9999-999999999999 pub viewFreeBusy

You can test going directory to the mailbox server by using the following example:

curl --insecure<Start Time>&e=<End Time>

We have seen issues where data from an appointment can cause Free/Busy lookup issues. To ensure that this is not occurring, you will need to export the calendar to an ICS file and import it into a test account. If Free/Busy issues still appear on the test account, please open a support case and include the .ics file for review.

A request from the web client will use soap calls. Within the /opt/zimbra/docs/soap-calendar.txt file there is an example of the soap call that is performed, here is the snippit of the example:

// GetFreeBusyRequest
// (f)ree (b)usy busy-(t)entative busy-(u)navailable or (n)o-data elements
  [uid="zimbraId/email,..."] // DEPRECATED
           // comma-separated list of zimraId or email
           // each value can be zimbraId or email
  [id="zimbraId,..."] // comma-separated list of zimbraId
  [name="email,..."] // comma-separated list of email
           // For accounts listed in uid/id/name above, f/b search will be done for all calendar folders.
           // To view free/busy for a single folder in a particular account, use the <usr> format below.
  [excludeUid="UID of appointment to exclude from free/busy search"]
  [<usr [id="zimbraId] [name="email"] // either id or email must be specified
     [l="folder id"] // calendar folder id; if omitted, get f/b on all calendar folders
  <usr id="id"> // id is always account email; it is not zimbraId as the attribute name may suggest
    <u s="START_MSECS_GMT" e="END_MSECS_GMT"/>* // a.k.a. out of office
    <n s="START_MSECS_GMT" e="END_MSECS_GMT"/>* // could not retrieve data for that user

The following is an example of a soap debug call that can be found within the mailbox.log:

2015-07-23 11:18:12,227 TRACE [qtp509886383-296252:https://10.999.99.99:8443/service/soap/GetFreeBusyRequest] [;;mid=9;ip=;ua=ZimbraWebClient - FF39 (Mac)/8.6.0_GA_1169;] soap - C:
<soap:Envelope xmlns:soap="">
<context xmlns="urn:zimbra">
<userAgent name="ZimbraWebClient - FF39 (Mac)" version="8.6.0_GA_1169"/>
<session id="1569"/>
<notify seq="1"/>
<account by="name"></account>
<format type="js"/>
<GetFreeBusyRequest uid="" s="1437634800000" e="1437721200000" excludeUid="-1" xmlns="urn:zimbraMail"/>

Free/Busy issue from Zimbra Connector for Outlook (ZCO) =

When Zimbra is using SSL, a known bug in Outlook 2013 limits the free/busy string. In this case, the URL created by Outlook during startup does not contain the session AUTHKEY. Due to the missing AUTHKEY, Zimbra determines that the request is coming from an unknown user so that the request will fail due to ACE rules or the rejection of the URL. We are currently waiting for Microsoft to address this limitation.

The ZCO connector does not call Free/Busy information but sets the Free/Busy Search string within the client. Because of this, the ZCO debug logging will not contain any logging of obtaining free busy data. During the startup of Outlook, the ZCO connector will reset the URL within File - Options - Calendar - Free Busy Options…


The Free/Busy URL created during startup will resemble the following:<Token>

To test the URL, the user or admin can update %name%@%server% with the email address of the user they wish to obtain Free/Busy data for. For example:<Token>

Then drop the string into any browser and an .ics file should be downloaded to the system. Open the .ics file and a successful download should contain data similar to this:


If the download does not contain the FREEBUSY data, then the issue is not on the Connector.

Additional Content

  • Not additional content
Verified Against: Zimbra Collaboration 8.6, 8.0 Date Created: 09/16/2015
Article ID: Date Modified: 2019-05-27

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Wiki/KB reviewed by SME1 SME2 Copyeditor Last edit by David Bingham
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