Some background information. It's OK if you don't understand it, it's admittedly too technical. This would have happened with any table. You see it with Admin Tools because it's simply the first table with a large index being restored. The problem has to do with your old site being hosted on an old server which doesn't support the UTF8MB4 encoding whereas the new one does and you're trying to upgrade the tables to the new encoding. This will only work if the extension tables support such a conversion. Admin Tools will only apply a workaround for this issue to its database tables if it runs on a server compatible with UTF8MB4. Since your old server wasn't compatible no workaround was applied. This wouldn't have been a problem if you were not trying to forcibly upgrade your tables to UTF8MB4 while restoring the site.
TL;DR: How to solve this problem. When you are restoring your site you reach the database restoration page. Enter your new database connection information.
Before clicking Next please make sure that on the right hand side of the screen the following checkboxes are
NOT checked:
- Force UTF-8 collation on database
- Force UTF-8 collation on tables
- Allow UTF8MB4 auto-detection
By doing that you are instructing ANGIE (the restoration script) to NOT attempt to modify the encoding of your tables.
If that still fails, even though it shouldn't, change the checkboxes per the following recommendations:
- Force UTF-8 collation on database: NOT checked
- Force UTF-8 collation on tables: CHECKED
- Allow UTF8MB4 auto-detection: NOT checked
This instructs ANGIE to forcibly change the encoding of the tables to plain old UTF-8.
In any case, after restoring your site please remember to update Admin Tools if necessary and definitely visit its control panel page to let it apply a workaround which will prevent any similar issues in the future (at least with Admin Tools' tables).
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!