Just in case it’s a database problem, please use PHPMYADMIN to analyze and, if necessary, repair your database. PHPMYADMIN is part of your hosting package. Try this search with the name of your host added to get specific instructions for your host: https://duckduckgo.com/?q=phpmyadmin+repair+database
Thank you very much for your input Steven, but I just checked the database through PHPMYADMIN like you suggested and everything seems to be okay there… Yet the problem persists with the same error message… Is there something else I should try?
Ask your host to review the MySQL server logs. Could you be running out of space?
I think I found the issue… I added emojis to the post, and tried to upload… And it refused to upload, but the moment I deleted all the emojis, the post uploaded. Does it mean the wordpress database does not recognise the emojis as characters for posts?
If you entered them through the editor, they should have been acceptable. How did you add an emoji?