Honestly, not really sure.

[SazzyP260]

MyBB has experienced an internal SQL error and cannot continue.
SQL Error: 144 - Table './lyric_mybb1/mybb_posts' is marked as crashed and last (automatic?) repair failed 
Query: SELECT COUNT(pid) AS draftcount FROM mybb_posts WHERE visible = '-2' AND uid = '43948'

This pops up whenever someone goes to click on a forum board or, really, anything that isn't the main page.

Forum Version is 1.8.3

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MyBB has experienced an internal SQL error and cannot continue.

SQL Error:144 - Table './lyric_mybb1/mybb_posts' is marked as crashed and last (automatic?) repair failedQuery:SELECT tid,uid FROM mybb_posts WHERE uid='43948' AND tid IN (13923,14310,11571,15485,15396,11404,15039,15481,15471,14358,15412,15118,15044,15033,15106,15187,14733,14970,14947,14912,14601,14430,14423,14280,14482,14463,14452,13843,13863,13842,14063,14284,5002,11999) AND visible IN (-1,0,1)

That's trying to get onto a forum board.

MyBB has experienced an internal SQL error and cannot continue.

SQL Error:144 - Table './lyric_mybb1/mybb_posts' is marked as crashed and last (automatic?) repair failedQuery:SELECT COUNT(*) AS newposts FROM mybb_posts WHERE dateline > '1583881399' AND visible='1'

That's entering the Admin CP - Can still use all of the functions in the CP but cannot access the front page.

[noyle]

This error has clearly explained itself, which is the table ./lyric_mybb1/mybb_posts is marked as crashed and repairing has been failed. It's not an error that MyBB can resolve. You may need to look into the database for investigation. Here's a post for reference: https://stackoverflow.com/a/13813363/6681141 .