add fix for locked migrations

docs/administration-guide.md

@@ -90,4 +90,23 @@ This is used in emails to allow users to click on a url to their specific instan
 This is used when doing date breakouts, and will set the default timezone for displaying all times. It does not change the timezone of any underlying data, however, if the underlying times don't have a timezone attached to them, this timezone is used.
 
 ### Name used for the instance
-If you want to give the instance a name (often the name of your company), you should set it here.
\ No newline at end of file
+If you want to give the instance a name (often the name of your company), you should set it here.
+
+
+## Common Problems
+
+### Startup fails due to Migrations being locked
+
+Sometimes Metabase will fail to startup due to a lingering lock. 
+
+Solution:
+Run  `java -cp metabase-master-2015-08-06-3da1178.jar org.h2.tools.Server -webPort 3000` in the commandline
+
+open the web console (it prints a url)
+
+connect to JDBC URL jdbc:h2:PATH/TO/metabase.db;IFEXISTS=TRUE  # note the .h2.db suffix is omitted
+blank username, blank password
+
+run `delete from databasechangeloglock;`
+
+kill the h2 server and restart metabase.