不幸的是，我通过自制软件升级到了postgis的2.2.0版本，现在出现了以下错误。我会回到2.1.0，但这个公式似乎已经不可用了。走向2.0试图将Postgres降级到9.2。
如果我想知道我还能尝试什么，我将不胜感激？
版本：
- PostGres:9.4.5_2
- Postgis：2.2.0
- activerecord_postgis_adapter:3.1.0
- pg宝石：0.18
以下错误：
PG::UndefinedFile - ERROR: could not access file "$libdir/postgis-2.1": No such file or directory
:
activerecord (4.2.4) lib/active_record/connection_adapters/postgresql_adapter.rb:596:in `block in exec_no_cache'
activerecord (4.2.4) lib/active_record/connection_adapters/abstract_adapter.rb:473:in `block in log'
activesupport (4.2.4) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activerecord (4.2.4) lib/active_record/connection_adapters/abstract_adapter.rb:467:in `log'
activerecord (4.2.4) lib/active_record/connection_adapters/postgresql_adapter.rb:596:in `exec_no_cache'
activerecord (4.2.4) lib/active_record/connection_adapters/postgresql_adapter.rb:588:in `execute_and_clear'
activerecord (4.2.4) lib/active_record/connection_adapters/postgresql/database_statements.rb:160:in `exec_query'
activerecord (4.2.4) lib/active_record/connection_adapters/postgresql_adapter.rb:737:in `column_definitions'
activerecord-postgis-adapter (3.1.0) lib/active_record/connection_adapters/postgis/schema_statements.rb:9:in `columns'
基本调试：
$ pg_config --pkglibdir
/usr/local/Cellar/postgresql/9.4.5/lib
$ ls -lrt /usr/local/Cellar/postgresql/9.4.5/lib/postgis
postgis-2.1.so*
/usr/local/Cellar/postgresql/仍然显示9.4.5_1和9.4.5_2的文件夹。我还尝试过在Postgres上删除、创建和更改postgis扩展，它运行起来没有问题。当我查找已安装的扩展时：
-[ RECORD 36 ]----+---------------------------------------------------------------------
name | postgis
default_version | 2.1.7
installed_version | 2.2.0
comment | PostGIS geometry, geography, and raster spatial types and functions
在带有自制程序的OSX上，我通常会同时更新postgresql和postgis，如下所示：
brew update
brew uninstall postgis
brew upgrade postgresql
brew install postgis
# update the postgis extension
psql -d your_database -c "alter extension postgis update"
# recompile the native extensions in the pg gem
gem pristine pg
如果您正在进行PostgreSQL的主要更新（例如，从9.4到9.5），并且希望保留您的数据，请首先查看pg_upgrade。
我也遇到了同样的问题，从postgres shell运行ALTER EXTENSION postgis UPDATE;似乎起到了作用：
$ dx postgis
| 2.1.7 | public | PostGIS geometry, geography, and raster spatial types and functions
$ ALTER EXTENSION postgis UPDATE;
ALTER EXTENSION
$ dx postgis
| 2.2.0 | public | PostGIS geometry, geography, and raster spatial types and functions
在那之后，错误消失了