Android 8.1 with iCloud, "No CalDAV/CardDAV service found"

Hello,
I am getting the error “No CalDAV/CardDAV service found” when trying to add an iCloud account. URL, name, and pw are checked. It worked on Android 6, but on Android 8 not. It seems apple blocks this request with new header/http/device information.

This line

2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] carddav service discovery failed

is different compared to post in
https://forums.bitfire.at/topic/1302/icloud-login-url/2
where it is

2017-01-11 10:24:15 4 [ui.setup.DavResourceFinder] Found carddav service at https://contacts.icloud.com:443
2017-01-11 10:24:15 4 [ui.setup.DavResourceFinder] Trying to determine principal from initial context path=https://contacts.icloud.com/.well-known/carddav

--- BEGIN DEBUG INFO ---

LOGS:
2018-11-23 17:26:30 320 [ui.setup.DavResourceFinder] Finding initial carddav service configuration
2018-11-23 17:26:30 320 [ui.setup.DavResourceFinder] Checking user-given URL: https://icloud.com/
2018-11-23 17:26:30 320 [HttpClient] --> PROPFIND https://icloud.com/
2018-11-23 17:26:30 320 [HttpClient] Content-Type: application/xml; charset=utf-8
2018-11-23 17:26:30 320 [HttpClient] Content-Length: 290
2018-11-23 17:26:30 320 [HttpClient] Depth: 0
2018-11-23 17:26:30 320 [HttpClient] 
2018-11-23 17:26:30 320 [HttpClient] <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><resourcetype /><displayname /><CARD:addressbook-description /><CARD:addressbook-home-set /><current-user-principal /></prop></propfind>
2018-11-23 17:26:30 320 [HttpClient] --> END PROPFIND (290-byte body)
2018-11-23 17:26:30 320 [HttpClient] <-- 301 Moved Permanently https://icloud.com/ (173ms)
2018-11-23 17:26:30 320 [HttpClient] Server: ATS/7.1.4
2018-11-23 17:26:30 320 [HttpClient] Date: Fri, 23 Nov 2018 16:26:30 GMT
2018-11-23 17:26:30 320 [HttpClient] Content-Length: 17
2018-11-23 17:26:30 320 [HttpClient] Cache-Control: no-cache
2018-11-23 17:26:30 320 [HttpClient] Pragma: no-cache
2018-11-23 17:26:30 320 [HttpClient] Location: https://www.icloud.com/
2018-11-23 17:26:30 320 [HttpClient] via: webedge:am02p00ic-ztde040709:5401:18RC30:Amsterdam, https/1.1 defra3-edge-bx-043.ts.apple.com (ApacheTrafficServer/7.1.4)
2018-11-23 17:26:30 320 [HttpClient] X-Apple-Request-UUID: 98f7c632-feea-4b22-91f2-d641ea39e221
2018-11-23 17:26:30 320 [HttpClient] access-control-expose-headers: X-Apple-Request-UUID
2018-11-23 17:26:30 320 [HttpClient] access-control-expose-headers: Via
2018-11-23 17:26:30 320 [HttpClient] Age: 0
2018-11-23 17:26:30 320 [HttpClient] Connection: keep-alive
2018-11-23 17:26:30 320 [HttpClient] CDNUUID: 21ca9e3c-e5aa-452c-acb5-ba54380fe74c-1180670922
2018-11-23 17:26:30 320 [HttpClient] X-Cache: skipped
2018-11-23 17:26:30 320 [HttpClient] 
2018-11-23 17:26:30 320 [HttpClient] Moved Permanently
2018-11-23 17:26:30 320 [HttpClient] <-- END HTTP (17-byte body)
2018-11-23 17:26:30 320 [DavResource] Redirected, new location = https://www.icloud.com/
2018-11-23 17:26:30 320 [HttpClient] --> PROPFIND https://www.icloud.com/
2018-11-23 17:26:30 320 [HttpClient] Content-Type: application/xml; charset=utf-8
2018-11-23 17:26:30 320 [HttpClient] Content-Length: 290
2018-11-23 17:26:30 320 [HttpClient] Depth: 0
2018-11-23 17:26:30 320 [HttpClient] 
2018-11-23 17:26:30 320 [HttpClient] <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><resourcetype /><displayname /><CARD:addressbook-description /><CARD:addressbook-home-set /><current-user-principal /></prop></propfind>
2018-11-23 17:26:30 320 [HttpClient] --> END PROPFIND (290-byte body)
2018-11-23 17:26:30 320 [HttpClient] <-- 501 Not Implemented https://www.icloud.com/ (145ms)
2018-11-23 17:26:30 320 [HttpClient] Server: AkamaiGHost
2018-11-23 17:26:30 320 [HttpClient] Mime-Version: 1.0
2018-11-23 17:26:30 320 [HttpClient] Content-Type: text/html
2018-11-23 17:26:30 320 [HttpClient] Content-Length: 244
2018-11-23 17:26:30 320 [HttpClient] Expires: Fri, 23 Nov 2018 16:26:30 GMT
2018-11-23 17:26:30 320 [HttpClient] Date: Fri, 23 Nov 2018 16:26:30 GMT
2018-11-23 17:26:30 320 [HttpClient] Connection: close
2018-11-23 17:26:30 320 [HttpClient] 
2018-11-23 17:26:30 320 [HttpClient] <HTML><HEAD>
<TITLE>Unsupported Request</TITLE>
</HEAD><BODY>
<H1>Unsupported Request</H1>
PROPFIND to http&#58;&#47;&#47;www&#46;icloud&#46;com&#47; not supported.<P>
Reference&#32;&#35;8&#46;4016068&#46;1542990390&#46;1224ba3c
</BODY></HTML>

2018-11-23 17:26:30 320 [HttpClient] <-- END HTTP (244-byte body)
2018-11-23 17:26:30 320 [ui.setup.DavResourceFinder] PROPFIND/OPTIONS on user-given URL failed
EXCEPTION at.bitfire.dav4android.exception.HttpException: HTTP 501 Not Implemented
	at at.bitfire.dav4android.DavResource.checkStatus(DavResource.kt:362)
	at at.bitfire.dav4android.DavResource.checkStatus(DavResource.kt:338)
	at at.bitfire.dav4android.DavResource.processMultiStatus(DavResource.kt:430)
	at at.bitfire.dav4android.DavResource.propfind(DavResource.kt:325)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.checkUserGivenURL(DavResourceFinder.kt:190)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:125)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:82)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:136)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:120)
	at android.support.v4.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:307)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:60)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:48)
	at android.support.v4.content.ModernAsyncTask$2.call(ModernAsyncTask.java:141)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
	at java.lang.Thread.run(Thread.java:764)

2018-11-23 17:26:30 320 [HttpClient] --> PROPFIND https://icloud.com/.well-known/carddav
2018-11-23 17:26:30 320 [HttpClient] Content-Type: application/xml; charset=utf-8
2018-11-23 17:26:30 320 [HttpClient] Content-Length: 198
2018-11-23 17:26:30 320 [HttpClient] Depth: 0
2018-11-23 17:26:30 320 [HttpClient] 
2018-11-23 17:26:30 320 [HttpClient] <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><current-user-principal /></prop></propfind>
2018-11-23 17:26:30 320 [HttpClient] --> END PROPFIND (198-byte body)
2018-11-23 17:26:30 320 [HttpClient] <-- 301 Moved Permanently https://icloud.com/.well-known/carddav (96ms)
2018-11-23 17:26:30 320 [HttpClient] Server: ATS/7.1.4
2018-11-23 17:26:30 320 [HttpClient] Date: Fri, 23 Nov 2018 16:26:30 GMT
2018-11-23 17:26:30 320 [HttpClient] Content-Length: 17
2018-11-23 17:26:30 320 [HttpClient] Cache-Control: no-cache
2018-11-23 17:26:30 320 [HttpClient] Pragma: no-cache
2018-11-23 17:26:30 320 [HttpClient] Location: https://www.icloud.com/.well-known/carddav
2018-11-23 17:26:30 320 [HttpClient] via: webedge:am02p00ic-ztde040705:5401:18RC30:Amsterdam, https/1.1 defra3-edge-bx-043.ts.apple.com (ApacheTrafficServer/7.1.4)
2018-11-23 17:26:30 320 [HttpClient] X-Apple-Request-UUID: 9c14388a-a1ba-4690-b944-c0ea042e201a
2018-11-23 17:26:30 320 [HttpClient] access-control-expose-headers: X-Apple-Request-UUID
2018-11-23 17:26:30 320 [HttpClient] access-control-expose-headers: Via
2018-11-23 17:26:30 320 [HttpClient] Age: 0
2018-11-23 17:26:30 320 [HttpClient] Connection: keep-alive
2018-11-23 17:26:30 320 [HttpClient] CDNUUID: 21ca9e3c-e5aa-452c-acb5-ba54380fe74c-1180671232
2018-11-23 17:26:30 320 [HttpClient] X-Cache: skipped
2018-11-23 17:26:30 320 [HttpClient] 
2018-11-23 17:26:30 320 [HttpClient] Moved Permanently
2018-11-23 17:26:30 320 [HttpClient] <-- END HTTP (17-byte body)
2018-11-23 17:26:30 320 [DavResource] Redirected, new location = https://www.icloud.com/.well-known/carddav
2018-11-23 17:26:30 320 [HttpClient] --> PROPFIND https://www.icloud.com/.well-known/carddav
2018-11-23 17:26:30 320 [HttpClient] Content-Type: application/xml; charset=utf-8
2018-11-23 17:26:30 320 [HttpClient] Content-Length: 198
2018-11-23 17:26:30 320 [HttpClient] Depth: 0
2018-11-23 17:26:30 320 [HttpClient] 
2018-11-23 17:26:30 320 [HttpClient] <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><current-user-principal /></prop></propfind>
2018-11-23 17:26:30 320 [HttpClient] --> END PROPFIND (198-byte body)
2018-11-23 17:26:31 320 [HttpClient] <-- 501 Not Implemented https://www.icloud.com/.well-known/carddav (125ms)
2018-11-23 17:26:31 320 [HttpClient] Server: AkamaiGHost
2018-11-23 17:26:31 320 [HttpClient] Mime-Version: 1.0
2018-11-23 17:26:31 320 [HttpClient] Content-Type: text/html
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 275
2018-11-23 17:26:31 320 [HttpClient] Expires: Fri, 23 Nov 2018 16:26:31 GMT
2018-11-23 17:26:31 320 [HttpClient] Date: Fri, 23 Nov 2018 16:26:31 GMT
2018-11-23 17:26:31 320 [HttpClient] Connection: close
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] <HTML><HEAD>
<TITLE>Unsupported Request</TITLE>
</HEAD><BODY>
<H1>Unsupported Request</H1>
PROPFIND to http&#58;&#47;&#47;www&#46;icloud&#46;com&#47;&#46;well&#45;known&#47;carddav not supported.<P>
Reference&#32;&#35;8&#46;4016068&#46;1542990391&#46;1224bb6a
</BODY></HTML>

2018-11-23 17:26:31 320 [HttpClient] <-- END HTTP (275-byte body)
2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] Well-known URL detection failed
EXCEPTION at.bitfire.dav4android.exception.HttpException: HTTP 501 Not Implemented
	at at.bitfire.dav4android.DavResource.checkStatus(DavResource.kt:362)
	at at.bitfire.dav4android.DavResource.checkStatus(DavResource.kt:338)
	at at.bitfire.dav4android.DavResource.processMultiStatus(DavResource.kt:430)
	at at.bitfire.dav4android.DavResource.propfind(DavResource.kt:325)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.getCurrentUserPrincipal(DavResourceFinder.kt:395)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:129)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:82)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:136)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:120)
	at android.support.v4.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:307)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:60)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:48)
	at android.support.v4.content.ModernAsyncTask$2.call(ModernAsyncTask.java:141)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
	at java.lang.Thread.run(Thread.java:764)

2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] No principal found at user-given URL, trying to discover
2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] Looking up SRV records for _carddavs._tcp.icloud.com
2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] carddav service discovery failed
EXCEPTION java.lang.ArrayIndexOutOfBoundsException: length=0; index=0
	at org.xbill.DNS.ExtendedResolver$Resolution.start(ExtendedResolver.java:102)
	at org.xbill.DNS.ExtendedResolver.send(ExtendedResolver.java:358)
	at org.xbill.DNS.Lookup.lookup(Lookup.java:477)
	at org.xbill.DNS.Lookup.resolve(Lookup.java:529)
	at org.xbill.DNS.Lookup.run(Lookup.java:543)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.discoverPrincipalUrl(DavResourceFinder.kt:341)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:148)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:82)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:136)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:120)
	at android.support.v4.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:307)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:60)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:48)
	at android.support.v4.content.ModernAsyncTask$2.call(ModernAsyncTask.java:141)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
	at java.lang.Thread.run(Thread.java:764)

2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] Finding initial caldav service configuration
2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] Checking user-given URL: https://icloud.com/
2018-11-23 17:26:31 320 [HttpClient] --> PROPFIND https://icloud.com/
2018-11-23 17:26:31 320 [HttpClient] Content-Type: application/xml; charset=utf-8
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 435
2018-11-23 17:26:31 320 [HttpClient] Depth: 0
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><resourcetype /><displayname /><n0:calendar-color xmlns:n0="http://apple.com/ns/ical/" /><CAL:calendar-description /><CAL:calendar-timezone /><current-user-privilege-set /><CAL:supported-calendar-component-set /><CAL:calendar-home-set /><current-user-principal /></prop></propfind>
2018-11-23 17:26:31 320 [HttpClient] --> END PROPFIND (435-byte body)
2018-11-23 17:26:31 320 [HttpClient] <-- 301 Moved Permanently https://icloud.com/ (89ms)
2018-11-23 17:26:31 320 [HttpClient] Server: ATS/7.1.4
2018-11-23 17:26:31 320 [HttpClient] Date: Fri, 23 Nov 2018 16:26:31 GMT
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 17
2018-11-23 17:26:31 320 [HttpClient] Cache-Control: no-cache
2018-11-23 17:26:31 320 [HttpClient] Pragma: no-cache
2018-11-23 17:26:31 320 [HttpClient] Location: https://www.icloud.com/
2018-11-23 17:26:31 320 [HttpClient] via: webedge:am02p00ic-ztde040623:5401:18RC30:Amsterdam, https/1.1 defra3-edge-bx-043.ts.apple.com (ApacheTrafficServer/7.1.4)
2018-11-23 17:26:31 320 [HttpClient] X-Apple-Request-UUID: 5a7dcf47-18f3-4165-9b5e-41b3cb47293c
2018-11-23 17:26:31 320 [HttpClient] access-control-expose-headers: X-Apple-Request-UUID
2018-11-23 17:26:31 320 [HttpClient] access-control-expose-headers: Via
2018-11-23 17:26:31 320 [HttpClient] Age: 0
2018-11-23 17:26:31 320 [HttpClient] Connection: keep-alive
2018-11-23 17:26:31 320 [HttpClient] CDNUUID: 21ca9e3c-e5aa-452c-acb5-ba54380fe74c-1180671451
2018-11-23 17:26:31 320 [HttpClient] X-Cache: skipped
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] Moved Permanently
2018-11-23 17:26:31 320 [HttpClient] <-- END HTTP (17-byte body)
2018-11-23 17:26:31 320 [DavResource] Redirected, new location = https://www.icloud.com/
2018-11-23 17:26:31 320 [HttpClient] --> PROPFIND https://www.icloud.com/
2018-11-23 17:26:31 320 [HttpClient] Content-Type: application/xml; charset=utf-8
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 435
2018-11-23 17:26:31 320 [HttpClient] Depth: 0
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><resourcetype /><displayname /><n0:calendar-color xmlns:n0="http://apple.com/ns/ical/" /><CAL:calendar-description /><CAL:calendar-timezone /><current-user-privilege-set /><CAL:supported-calendar-component-set /><CAL:calendar-home-set /><current-user-principal /></prop></propfind>
2018-11-23 17:26:31 320 [HttpClient] --> END PROPFIND (435-byte body)
2018-11-23 17:26:31 320 [HttpClient] <-- 501 Not Implemented https://www.icloud.com/ (127ms)
2018-11-23 17:26:31 320 [HttpClient] Server: AkamaiGHost
2018-11-23 17:26:31 320 [HttpClient] Mime-Version: 1.0
2018-11-23 17:26:31 320 [HttpClient] Content-Type: text/html
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 244
2018-11-23 17:26:31 320 [HttpClient] Expires: Fri, 23 Nov 2018 16:26:31 GMT
2018-11-23 17:26:31 320 [HttpClient] Date: Fri, 23 Nov 2018 16:26:31 GMT
2018-11-23 17:26:31 320 [HttpClient] Connection: close
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] <HTML><HEAD>
<TITLE>Unsupported Request</TITLE>
</HEAD><BODY>
<H1>Unsupported Request</H1>
PROPFIND to http&#58;&#47;&#47;www&#46;icloud&#46;com&#47; not supported.<P>
Reference&#32;&#35;8&#46;4016068&#46;1542990391&#46;1224bc70
</BODY></HTML>

2018-11-23 17:26:31 320 [HttpClient] <-- END HTTP (244-byte body)
2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] PROPFIND/OPTIONS on user-given URL failed
EXCEPTION at.bitfire.dav4android.exception.HttpException: HTTP 501 Not Implemented
	at at.bitfire.dav4android.DavResource.checkStatus(DavResource.kt:362)
	at at.bitfire.dav4android.DavResource.checkStatus(DavResource.kt:338)
	at at.bitfire.dav4android.DavResource.processMultiStatus(DavResource.kt:430)
	at at.bitfire.dav4android.DavResource.propfind(DavResource.kt:325)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.checkUserGivenURL(DavResourceFinder.kt:199)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:125)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:89)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:136)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:120)
	at android.support.v4.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:307)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:60)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:48)
	at android.support.v4.content.ModernAsyncTask$2.call(ModernAsyncTask.java:141)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
	at java.lang.Thread.run(Thread.java:764)

2018-11-23 17:26:31 320 [HttpClient] --> PROPFIND https://icloud.com/.well-known/caldav
2018-11-23 17:26:31 320 [HttpClient] Content-Type: application/xml; charset=utf-8
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 198
2018-11-23 17:26:31 320 [HttpClient] Depth: 0
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><current-user-principal /></prop></propfind>
2018-11-23 17:26:31 320 [HttpClient] --> END PROPFIND (198-byte body)
2018-11-23 17:26:31 320 [HttpClient] <-- 301 Moved Permanently https://icloud.com/.well-known/caldav (83ms)
2018-11-23 17:26:31 320 [HttpClient] Server: ATS/7.1.4
2018-11-23 17:26:31 320 [HttpClient] Date: Fri, 23 Nov 2018 16:26:31 GMT
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 17
2018-11-23 17:26:31 320 [HttpClient] Cache-Control: no-cache
2018-11-23 17:26:31 320 [HttpClient] Pragma: no-cache
2018-11-23 17:26:31 320 [HttpClient] Location: https://www.icloud.com/.well-known/caldav
2018-11-23 17:26:31 320 [HttpClient] via: webedge:am02p00ic-ztde040621:5401:18RC30:Amsterdam, https/1.1 defra3-edge-bx-043.ts.apple.com (ApacheTrafficServer/7.1.4)
2018-11-23 17:26:31 320 [HttpClient] X-Apple-Request-UUID: d1fcdfe9-10e4-4a42-b76d-b5c303962ac8
2018-11-23 17:26:31 320 [HttpClient] access-control-expose-headers: X-Apple-Request-UUID
2018-11-23 17:26:31 320 [HttpClient] access-control-expose-headers: Via
2018-11-23 17:26:31 320 [HttpClient] Age: 0
2018-11-23 17:26:31 320 [HttpClient] Connection: keep-alive
2018-11-23 17:26:31 320 [HttpClient] CDNUUID: 21ca9e3c-e5aa-452c-acb5-ba54380fe74c-1180671641
2018-11-23 17:26:31 320 [HttpClient] X-Cache: skipped
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] Moved Permanently
2018-11-23 17:26:31 320 [HttpClient] <-- END HTTP (17-byte body)
2018-11-23 17:26:31 320 [DavResource] Redirected, new location = https://www.icloud.com/.well-known/caldav
2018-11-23 17:26:31 320 [HttpClient] --> PROPFIND https://www.icloud.com/.well-known/caldav
2018-11-23 17:26:31 320 [HttpClient] Content-Type: application/xml; charset=utf-8
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 198
2018-11-23 17:26:31 320 [HttpClient] Depth: 0
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><current-user-principal /></prop></propfind>
2018-11-23 17:26:31 320 [HttpClient] --> END PROPFIND (198-byte body)
2018-11-23 17:26:31 320 [HttpClient] <-- 501 Not Implemented https://www.icloud.com/.well-known/caldav (130ms)
2018-11-23 17:26:31 320 [HttpClient] Server: AkamaiGHost
2018-11-23 17:26:31 320 [HttpClient] Mime-Version: 1.0
2018-11-23 17:26:31 320 [HttpClient] Content-Type: text/html
2018-11-23 17:26:31 320 [HttpClient] Content-Length: 274
2018-11-23 17:26:31 320 [HttpClient] Expires: Fri, 23 Nov 2018 16:26:31 GMT
2018-11-23 17:26:31 320 [HttpClient] Date: Fri, 23 Nov 2018 16:26:31 GMT
2018-11-23 17:26:31 320 [HttpClient] Connection: close
2018-11-23 17:26:31 320 [HttpClient] 
2018-11-23 17:26:31 320 [HttpClient] <HTML><HEAD>
<TITLE>Unsupported Request</TITLE>
</HEAD><BODY>
<H1>Unsupported Request</H1>
PROPFIND to http&#58;&#47;&#47;www&#46;icloud&#46;com&#47;&#46;well&#45;known&#47;caldav not supported.<P>
Reference&#32;&#35;8&#46;4016068&#46;1542990391&#46;1224bda3
</BODY></HTML>

2018-11-23 17:26:31 320 [HttpClient] <-- END HTTP (274-byte body)
2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] Well-known URL detection failed
EXCEPTION at.bitfire.dav4android.exception.HttpException: HTTP 501 Not Implemented
	at at.bitfire.dav4android.DavResource.checkStatus(DavResource.kt:362)
	at at.bitfire.dav4android.DavResource.checkStatus(DavResource.kt:338)
	at at.bitfire.dav4android.DavResource.processMultiStatus(DavResource.kt:430)
	at at.bitfire.dav4android.DavResource.propfind(DavResource.kt:325)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.getCurrentUserPrincipal(DavResourceFinder.kt:395)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:129)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:89)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:136)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:120)
	at android.support.v4.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:307)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:60)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:48)
	at android.support.v4.content.ModernAsyncTask$2.call(ModernAsyncTask.java:141)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
	at java.lang.Thread.run(Thread.java:764)

2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] No principal found at user-given URL, trying to discover
2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] Looking up SRV records for _caldavs._tcp.icloud.com
2018-11-23 17:26:31 320 [ui.setup.DavResourceFinder] caldav service discovery failed
EXCEPTION java.lang.ArrayIndexOutOfBoundsException: length=0; index=0
	at org.xbill.DNS.ExtendedResolver$Resolution.start(ExtendedResolver.java:102)
	at org.xbill.DNS.ExtendedResolver.send(ExtendedResolver.java:358)
	at org.xbill.DNS.Lookup.lookup(Lookup.java:477)
	at org.xbill.DNS.Lookup.resolve(Lookup.java:529)
	at org.xbill.DNS.Lookup.run(Lookup.java:543)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.discoverPrincipalUrl(DavResourceFinder.kt:341)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:148)
	at at.bitfire.davdroid.ui.setup.DavResourceFinder.findInitialConfiguration(DavResourceFinder.kt:89)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:136)
	at at.bitfire.davdroid.ui.setup.DetectConfigurationFragment$ServerConfigurationLoader.loadInBackground(DetectConfigurationFragment.kt:120)
	at android.support.v4.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:307)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:60)
	at android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:48)
	at android.support.v4.content.ModernAsyncTask$2.call(ModernAsyncTask.java:141)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
	at java.lang.Thread.run(Thread.java:764)



SOFTWARE INFORMATION
Package: at.bitfire.davdroid
Version: 2.0.5-ose (248) from 07.11.2018
Installed from: com.android.packageinstaller
JB Workaround installed: no

CONNECTIVITY (at the moment)
Active connection: WiFi, CONNECTED

CONFIGURATION
Power saving disabled: yes
android.permission.READ_CONTACTS permission: granted
android.permission.WRITE_CONTACTS permission: granted
android.permission.READ_CALENDAR permission: granted
android.permission.WRITE_CALENDAR permission: granted
org.dmfs.permission.READ_TASKS permission: granted
org.dmfs.permission.WRITE_TASKS permission: granted
System-wide synchronization: automatically

SQLITE DUMP
android_metadata
	|  locale |
	|  de_DE |
----------
services
	|  _id | accountName | service | principal |
----------
sqlite_sequence
	|  name | seq |
----------
homesets
	|  _id | serviceID | url |
----------
collections
	|  _id | serviceID | type | url | privWriteContent | privUnbind | forceReadOnly | displayName | description | color | timezone | supportsVEVENT | supportsVTODO | source | sync |
----------

SYSTEM INFORMATION
Android version: 8.1.0 (unknown)
Device: unknown unknown (unknown)

--- END DEBUG INFO ---

Somehow the auto-detection in ui.setup.DavResourceFinder does not work for me, however there’s a workaround:

One account for calendar, basis-URL: https://p45-caldav.icloud.com
One account for contacts, basis-URL: https://p04-contacts.icloud.com/[uniqueid]/carddavhome/card/

uniqueid can be found in calendar log or xhr when going to icloud.com

rfc2822

Sounds like iCloud has changed their redirects, maybe temporarily? Sometimes this happens and then it works again some time later…

Android 8.1 with iCloud, "No CalDAV/CardDAV service found"

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