i think the extract below from the 'Plesk autoupdate failure report' speaks for itself:
...
Downloading the file PSA_8.6.0/dist-rpm-CentOS-4.2-i386/build-8.6.0-cos4.2-i386.hdr.gz: 10%..20%..30%..40%..50%..60%..70%..80%..90%..100% done.
Downloading the file PSA_8.6.0/update-rpm-CentOS-4.2-i386/update-8.6.0-cos4.2-i386.hdr.gz: 10%..20%..30%..40%..50%..60%..70%..80%..90%..100% done.
Downloading the file PSA_8.6.0/thirdparty-rpm-CentOS-4.2-i386/thirdparty-8.6.0-cos4.2-i386.hdr.gz: 14%..24%..33%..43%..52%..62%..72%..81%..91%..100% done.
Determining the packages that need to be installed.
Package courier-imap-3.0.8-cos4.build86080930.08.i586 from inf3 file not found in build headers (hdr.gz) file.ERROR: The auto-installer's configuration files .inf3 and .hdr.gz contain lists of packages that do not match.
Not all packages were installed.
Please, contact product technical support.
...
Downloading the file PSA_8.6.0/dist-rpm-CentOS-4.2-i386/build-8.6.0-cos4.2-i386.hdr.gz: 10%..20%..30%..40%..50%..60%..70%..80%..90%..100% done.
Downloading the file PSA_8.6.0/update-rpm-CentOS-4.2-i386/update-8.6.0-cos4.2-i386.hdr.gz: 10%..20%..30%..40%..50%..60%..70%..80%..90%..100% done.
Downloading the file PSA_8.6.0/thirdparty-rpm-CentOS-4.2-i386/thirdparty-8.6.0-cos4.2-i386.hdr.gz: 14%..24%..33%..43%..52%..62%..72%..81%..91%..100% done.
Determining the packages that need to be installed.
Package courier-imap-3.0.8-cos4.build86080930.08.i586 from inf3 file not found in build headers (hdr.gz) file.ERROR: The auto-installer's configuration files .inf3 and .hdr.gz contain lists of packages that do not match.
Not all packages were installed.
Please, contact product technical support.