Roundcube compose window - 'Save' button greyed out

[thoatswold]

For the last few days the 'Save' button has been greyed out in the compose window. I have no idea why; it didn't use to be like that. Otherwise everything is working fine. Any ideas, anyone?

My system is:
Ubuntu 18.04 server (64-bit)
PHP 7.2
mysql provided by MariaDB (mysql Ver 15.1 Distrib 10.1.29-MariaDB)
Postfix+Dovecot
Roundcube 1.3.6

[JohnDoh]

What did you change a few days ago? Are there any JS errors in the browser console? Try with all rc plugins disabled. Double check you have a drafts folder defined under settings > special folders

[thoatswold]

What did you change a few days ago? Are there any JS errors in the browser console? Try with all rc plugins disabled. Double check you have a drafts folder defined under settings > special folders

It was your last suggestion – the special folders, which I had set originally, had all somehow become unset (---), I have no idea how. I was not aware of having changed anything when the problem arose.

Having set them correctly again, the 'Save' button is now active. Thank you!

Phil