(-30975, 'DB_RUNRECOVERY: Fatal error, run database recovery -- PANIC: Invalid argument').
What to do now? ===
It is advisable not to click the repair button right away. It should work, but GRAMPS might believe an error is present while this is in reality not true. Repairing your tree then will lead to loss of the last typed changes.
Instead, take a backup of the family tree that is given problems. In a terminal do:
This will give you a list with all family trees and the directory where they are stored, normally somewhere in the directory ~/.gramps/grampsdb. Copy the directory of the tree with problems so as to have a backup:
target directory> < backup directory>
If the recover button was present on the GRAMPS family tree, click it. All should work again. If you notice you lost information, or the repair button does not work, then do the following.