github.com/brahmaroutu/docker@v1.2.1-0.20160809185609-eb28dde01f16/docs/breaking_changes.md (about) 1 <!--[metadata]> 2 +++ 3 aliases = ["/engine/misc/breaking/"] 4 title = "Breaking changes" 5 description = "Breaking changes" 6 keywords = ["docker, documentation, about, technology, breaking", 7 "incompatibilities"] 8 [menu.main] 9 parent = "engine_use" 10 weight=80 11 +++ 12 <![end-metadata]--> 13 14 # Breaking changes and incompatibilities 15 16 Every Engine release strives to be backward compatible with its predecessors. 17 In all cases, the policy is that feature removal is communicated two releases 18 in advance and documented as part of the [deprecated features](deprecated.md) 19 page. 20 21 Unfortunately, Docker is a fast moving project, and newly introduced features 22 may sometime introduce breaking changes and/or incompatibilities. This page 23 documents these by Engine version. 24 25 # Engine 1.12 26 27 Docker clients <= 1.9.2 used an invalid Host header when making request to the 28 daemon. Docker 1.12 is built using golang 1.6 which is now checking the validity 29 of the Host header and as such clients <= 1.9.2 can't talk anymore to the daemon. 30 [An environment variable was added to overcome this issue.](reference/commandline/dockerd.md#miscellaneous-options) 31 32 # Engine 1.10 33 34 There were two breaking changes in the 1.10 release. 35 36 ## Registry 37 38 Registry 2.3 includes improvements to the image manifest that have caused a 39 breaking change. Images pushed by Engine 1.10 to a Registry 2.3 cannot be 40 pulled by digest by older Engine versions. A `docker pull` that encounters this 41 situation returns the following error: 42 43 ``` 44 Error response from daemon: unsupported schema version 2 for tag TAGNAME 45 ``` 46 47 Docker Content Trust heavily relies on pull by digest. As a result, images 48 pushed from the Engine 1.10 CLI to a 2.3 Registry cannot be pulled by older 49 Engine CLIs (< 1.10) with Docker Content Trust enabled. 50 51 If you are using an older Registry version (< 2.3), this problem does not occur 52 with any version of the Engine CLI; push, pull, with and without content trust 53 work as you would expect. 54 55 ## Docker Content Trust 56 57 Engine older than the current 1.10 cannot pull images from repositories that 58 have enabled key delegation. Key delegation is a feature which requires a 59 manual action to enable.