Comment 6 for bug 1002500

@Mrten,

I tested with 5.1.65 and it seems to be going well.

Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 3 reinstalled, 0 to remove and 11 not upgraded.
Need to get 0 B/49.6 MB of archives.
After this operation, 0 B of additional disk space will be used.
Preconfiguring packages ...
(Reading database ... 61081 files and directories currently installed.)
Preparing to replace percona-server-server-5.1 5.1.65-rel14.0-475.precise (using .../percona-server-server-5.1_5.1.65-rel14.0-475.precise_amd64.deb) ...
 * Stopping MySQL (Percona Server) mysqld [ OK ]
 * Stopping MySQL (Percona Server) mysqld [ OK ]
Unpacking replacement percona-server-server-5.1 ...
Preparing to replace percona-server-client-5.1 5.1.65-rel14.0-475.precise (using .../percona-server-client-5.1_5.1.65-rel14.0-475.precise_amd64.deb) ...
Unpacking replacement percona-server-client-5.1 ...
Preparing to replace percona-server-common 5.1.65-rel14.0-475.precise (using .../percona-server-common_5.1.65-rel14.0-475.precise_amd64.deb) ...
Unpacking replacement percona-server-common ...
Processing triggers for ureadahead ...
Processing triggers for man-db ...
Setting up percona-server-common (5.1.65-rel14.0-475.precise) ...
Setting up percona-server-client-5.1 (5.1.65-rel14.0-475.precise) ...
Setting up percona-server-server-5.1 (5.1.65-rel14.0-475.precise) ...
 * Stopping MySQL (Percona Server) mysqld [ OK ]
Percona Server is distributed with several useful UDF (User Defined Function) from Maatkit.
Run the following commands to create these functions:
mysql -e "CREATE FUNCTION fnv1a_64 RETURNS INTEGER SONAME 'libfnv1a_udf.so'"
mysql -e "CREATE FUNCTION fnv_64 RETURNS INTEGER SONAME 'libfnv_udf.so'"
mysql -e "CREATE FUNCTION murmur_hash RETURNS INTEGER SONAME 'libmurmur_udf.so'"
See http://code.google.com/p/maatkit/source/browse/trunk/udf for more details
 * Starting MySQL (Percona Server) mysqld [ OK ]
 * Checking for corrupt, not cleanly closed and upgrade needing tables.
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place

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In your case it looks like the restart failed after the server started (since I see a [OK] there), so it may be something related to /etc/mysql/debian-start (which does mysql_upgrade etc.) or so.

Also, I have seen that /etc/init.d/mysql has changed a bit.

So, can you check in the syslog about probable causes of failed init? Also, let us know if it fails with latest package.