I've just updated a wiki that was at Mediawiki 1.20, and had previously been updated before, to the newest version 1.27.1.

Everything went very well! However upon usage I found that a protected page that had been moved in the long past, when opening for edition, spit out errors - which wasn't the case before the update.

The errors were:

<b>Notice</b>:  Undefined offset: 3 in <b>/var/websites/sp-mw/includes/logging/ProtectLogFormatter.php</b> on line <b>35</b>
<b>Notice</b>:  Undefined offset: 3 in <b>/var/websites/sp-mw/includes/logging/ProtectLogFormatter.php</b> on line <b>72</b>

I figured from the code that it was related with 'log_params' not being defined for that item in table 'logging'.

Apparently, during the update process what should have gone into 'log_params' was instead set as 'log_comment' during the database update (I'm guessing).

Anyway, when I changed the database so that

|    291 | protect  | move_prot  | 20090402141948 |        2 | Nevinho       |             0 | Sexta_poética        |        0 | Poema do dia |                                                      |           0 |

became

|    291 | protect  | move_prot  | 20090402141948 |        2 | Nevinho       |             0 | Sexta_poética        |        0 | Poema do dia | Poema do dia                                         |           0 |

Everything worked and the message down the page also changed from a "from to DESTINATION" statement to a proper "from ORIGIN to DESTINATION" statement.

Hope this can get fixed in the updater or somewhere else for other people updating like me.

Cheers!