(Please note that the Dolibarr wiki provides different and contradictory instructions here: Installation - Upgrade - Dolibarr ERP CRM Wiki
This instructs the install.lock file to be placed under the root directory in the first bullet point but then under /documents/ in the second. However, this “documents” directory does not exist post-install. This caused some confusion for me and might for other people.)
This should clear up any confusion:
I looked in my conf/conf.php file and found the following line:
$dolibarr_main_document_root=‘/home/XXX/erp’; (where XXX is my main root directory for my website, I’m just hiding it so as to not confuse anyone reading this). This is the same directory that priojk mentioned above as listed next to “Web server’s root directory”, just a different way of accessing it. Alternatively if you do Home → Admin Tools → Upgrade / Extend, after the check page you will see “Step 3: Remove/rename file /home/XXX/dolib/install.lock if it exists, to allow usage of the Update/Install tool.” once again, referencing the root directory.
In the meantime I will suggest a change to the wiki as it’s a bit confusing.