MySQL Bugs: #88808: InnoDB errors on mysql db tables when using innodb-force-recovery

Bug #88808	InnoDB errors on mysql db tables when using innodb-force-recovery
Submitted:	7 Dec 2017 10:03	Modified:	1 Jan 2018 22:23
Reporter:	Roel Van de Paar	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S1 (Critical)
Version:	5.7.20	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
2017-12-07T09:31:55.097575Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`server_cost` in the cache. Attempting to load the tablespace with space id 19
2017-12-07T09:31:55.098634Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`engine_cost` in the cache. Attempting to load the tablespace with space id 20
2017-12-07T09:31:55.101186Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone_leap_second` in the cache. Attempting to load the tablespace with space id 12
2017-12-07T09:31:55.102157Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone_name` in the cache. Attempting to load the tablespace with space id 8
2017-12-07T09:31:55.103525Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone` in the cache. Attempting to load the tablespace with space id 9
2017-12-07T09:31:55.104618Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone_transition_type` in the cache. Attempting to load the tablespace with space id 11
2017-12-07T09:31:55.105511Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone_transition` in the cache. Attempting to load the tablespace with space id 10
2017-12-07T09:31:55.107652Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`servers` in the cache. Attempting to load the tablespace with space id 3
2017-12-07T09:31:55.109381Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`slave_master_info` in the cache. Attempting to load the tablespace with space id 16
2017-12-07T09:31:55.110715Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`slave_relay_log_info` in the cache. Attempting to load the tablespace with space id 15
2017-12-07T09:31:55.112680Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`slave_worker_info` in the cache. Attempting to load the tablespace with space id 17

How to repeat:
Use --innodb-force-recovery=25 option to mysqld, startup/shutdown, then check error log.

Btw, 25 is non-specific; 
[Warning] option 'innodb-force-recovery': unsigned value 25 adjusted to 6

Roel, my dear friend,

I managed to repeat the same behaviour:

2017-12-07T15:20:39.415164Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`server_cost` in the cache. Attempting to load the tablespace with space id 19
2017-12-07T15:20:39.423669Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`engine_cost` in the cache. Attempting to load the tablespace with space id 20
2017-12-07T15:20:39.468220Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone_leap_second` in the cache. Attempting to load the tablespace with space id 12
2017-12-07T15:20:39.476505Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone_name` in the cache. Attempting to load the tablespace with space id 8
2017-12-07T15:20:39.484780Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone` in the cache. Attempting to load the tablespace with space id 9
2017-12-07T15:20:39.493216Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone_transition_type` in the cache. Attempting to load the tablespace with space id 11
2017-12-07T15:20:39.501675Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`time_zone_transition` in the cache. Attempting to load the tablespace with space id 10
2017-12-07T15:20:39.521628Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`servers` in the cache. Attempting to load the tablespace with space id 3
2017-12-07T15:20:39.531197Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`slave_master_info` in the cache. Attempting to load the tablespace with space id 16
2017-12-07T15:20:39.539824Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`slave_relay_log_info` in the cache. Attempting to load the tablespace with space id 15
2017-12-07T15:20:39.549069Z 0 [ERROR] InnoDB: Failed to find tablespace for table `mysql`.`slave_worker_info` in the cache. Attempting to load the tablespace with space id 17

Verified as reported.

Developers; what is the cause please? Impact?