Ubuntu 9.04 doesn`t upgrade

I can`t upgrade my Ubuntu 9.04 Desktop system.

I try : sudo apt-get update

everything works ok then:

sudo apt-get upgrade

then i get an error:

****************************************************************************************************************
(Reading database ... 143937 files and directories currently installed.)
Preparing to replace apturl 0.3.3ubuntu1 (using .../apturl_0.3.3ubuntu1.1_all.deb) ...
Traceback (most recent call last):
  File "/usr/bin/pycentral", line 2190, in <module>
    main()
  File "/usr/bin/pycentral", line 2184, in main
    rv = action.run(global_options)
  File "/usr/bin/pycentral", line 1638, in run
    runtimes = get_installed_runtimes(with_unsupported=True)
  File "/usr/bin/pycentral", line 276, in get_installed_runtimes
    default_version = pyversions.default_version(version_only=True)
  File "/usr/share/pycentral-data/pyversions.py", line 172, in default_version
    raise ValueError, "/usr/bin/python does not match the python default version. It must be reset to point to %s" % debian_default
ValueError: /usr/bin/python does not match the python default version. It must be reset to point to python2.6
dpkg: warning - old pre-removal script returned error exit status 1
dpkg - trying script from the new package instead ...
Traceback (most recent call last):
  File "/usr/bin/pycentral", line 2190, in <module>
    main()
  File "/usr/bin/pycentral", line 2184, in main
    rv = action.run(global_options)
  File "/usr/bin/pycentral", line 1638, in run
    runtimes = get_installed_runtimes(with_unsupported=True)
  File "/usr/bin/pycentral", line 276, in get_installed_runtimes
    default_version = pyversions.default_version(version_only=True)
  File "/usr/share/pycentral-data/pyversions.py", line 172, in default_version
    raise ValueError, "/usr/bin/python does not match the python default version. It must be reset to point to %s" % debian_default
ValueError: /usr/bin/python does not match the python default version. It must be reset to point to python2.6
dpkg: error processing /var/cache/apt/archives/apturl_0.3.3ubuntu1.1_all.deb (--unpack):
 subprocess new pre-removal script returned error exit status 1
Traceback (most recent call last):
  File "/usr/bin/pycentral", line 2190, in <module>
    main()
  File "/usr/bin/pycentral", line 2184, in main
    rv = action.run(global_options)
  File "/usr/bin/pycentral", line 1472, in run
    runtimes = get_installed_runtimes()
  File "/usr/bin/pycentral", line 276, in get_installed_runtimes
    default_version = pyversions.default_version(version_only=True)
  File "/usr/share/pycentral-data/pyversions.py", line 172, in default_version
    raise ValueError, "/usr/bin/python does not match the python default version. It must be reset to point to %s" % debian_default
ValueError: /usr/bin/python does not match the python default version. It must be reset to point to python2.6
dpkg: error while cleaning up:
 subprocess post-installation script returned error exit status 1
Errors were encountered while processing:
 /var/cache/apt/archives/apturl_0.3.3ubuntu1.1_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
**************************************************************************************************************

I don`t get it...in /usr/share/python/debian_defaults

# the default python version
default-version = python2.6

# all supported python versions
supported-versions = python2.5, python2.6

# formerly supported python versions
old-versions = python2.3, python2.4

# unsupported versions, including older versions
unsupported-versions = python2.3, python2.4

Any ideea how to fix???

Now i can`t install any package.... :(