InnoDB Failed to drop table causing crash.

i have recently hit an issue with our Percona instance and am wonderign if its an error anyone has seen before or coudl assist with. We are running version 5.7.21-20 and recieved the following error when a conrete5 job tried to perform some housekeeping of the database:

2018-06-08T00:01:22.497336Z 9 [Note] InnoDB: MySQL is trying to drop table c5.FTS_0000000000000a42_00000000000013ad_INDEX_1 though there are still open handles to it. Adding the table to the background drop queue.
2018-06-08T00:01:22.993845Z 9 [Note] InnoDB: MySQL is trying to drop table c5.FTS_0000000000000a42_00000000000013bb_INDEX_1 though there are still open handles to it. Adding the table to the background drop queue.
2018-06-08 00:01:23 0x7f81d1ffb700 InnoDB: Assertion failure in thread 140195550705408 in file line 822
InnoDB: Failing assertion: sym_node->table != NULL
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: about forcing recovery.
00:01:23 UTC - mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
Attempting to collect some information that could help diagnose the problem.
As this is a crash and something is definitely wrong, the information
collection process might fail.
Please help us make Percona XtraDB Cluster better by reporting any
bugs at

It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 212322 K bytes of memory
Hope that’s ok; if not, decrease some variables in the equation.

Thread pointer: 0x0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong…
stack_bottom = 0 thread_stack 0x40000
You may download the Percona XtraDB Cluster operations manual by visiting You may find information
in the manual which will help you identify the cause of the crash.
Log of wsrep recovery (–wsrep-recover):

I have had a search around on the web but cant seem to find anythign that points me int he right direction. One thing to note is that prior to the housekeepign job running the databse was restored from another environment, whereby the databse was dropped then recreated, i was wondering if this is at the root cause f the issue.

Any assistance gratefully recived.

Thanks in advance