you have only attached the latest log file. What went wrong was before that
I cannot find the error Key not valid for use in specified state within the log you supplied.
What i see is that attempts to download codecs failing - rate limited. This arises if you do a lot of installs/delete app data / re install in short period of time
Wait an hout after the last 429 error - as in here
Sep 09, 2018 01:54:25.170 [12496] DEBUG - HTTP requesting GET https://plex.tv/api/codecs/h264_decoder?build=windows-i386&deviceId=7862b89d-28b6-4500-b106-2be5b015d4b1&oldestPreviousVersion=1%2E1%2E4%2E2757-24ffd60&version=e7828f1-1324
Sep 09, 2018 01:54:26.402 [12496] DEBUG - HTTP 429 response from GET https://plex.tv/api/codecs/h264_decoder?build=windows-i386&deviceId=7862b89d-28b6-4500-b106-2be5b015d4b1&oldestPreviousVersion=1%2E1%2E4%2E2757-24ffd60&version=e7828f1-1324
Sep 09, 2018 01:54:26.403 [12496] ERROR - Codecs: Failed to download XML for codec 'h264_decoder'
and then try to play back H264 video and if it fails - download the logs and attach. Need to see the first error code and not the 429 errors later
It is possible that the original error was Key not valid for use in specified state but you did not provide logs to confirm that. The only known fix for this error is the purging of the windows rsa directory and possible a reboot after that
There were some user reports that they needed to rename the parent directory
See Transcoder Crashing after update to Plex Pass v. 1.11.1.4730 from 1.9.x - #42 by Jason.likens
