On October 3rd 2022, Google will disable an authentication flow used by Odoo for the Google Drive and Google Spreadsheet integrations. This will impact the flows of both modules currently supported in Odoo (versions 13.0 to 15.3).
In this blog post, we’ll demonstrate how you can keep working with Google Drive documents inside of Odoo after this change with minimal impact to your workflows.
What's happening?
Google is deprecating the so-called “out-of-band” authentication flow, which was used to allow a Google Drive application controlled by us to create or modify documents in your Google Drive account. The architecture of Odoo means this change cannot be transparently managed on our end without some degradation of the experience. We have instead decided to update currently supported versions of Odoo and to keep the feature as viable as possible, depending on the use case. This means that the experience for both integrations will be degraded.
How can I keep working with Google Drive after October 3rd?
Google Drive
The Google Drive integration (enabled via Settings > General Settings > Integrations > Google Drive) allows you to easily create a Google Doc from an existing document template and link it as a “virtual attachment” on an existing record in your Odoo database.
This feature will no longer work in any version of Odoo after October 3rd. Since the feature itself is rather limited in its capabilities, you can bypass this change by simply duplicating a template document manually in Google Drive and pasting the link to that document in the messaging area of the record (e.g. as a note or a message) or in a descriptive field of the underlying record (like Internal Notes on contacts, etc.).
All attachments created via this integration will continue working even after that date, but it will not be possible to create new ones.
Google Spreadsheet
The Google Spreadsheet integration (enabled via Settings > General Settings > Integrations > Google Spreadsheet) allows users to insert (and later, update) data from Odoo directly into a Google Spreadsheet, like a list of contacts or prospects.
This integration will keep working with a degraded experience:
a. Odoo will no longer be able to create the document in your Drive account by itself
b. Odoo credentials will have to be set up in the spreadsheet manually by the user
c. The formula to fetch the data inside the spreadsheet must be input by the user
After October 3rd, attempting to generate a new Google Spreadsheet from Odoo will behave like this:
1. Click on the “Add to Google Spreadsheet” button, as before
2. A dialog appears explaining how to proceed. As a first step, you must duplicate a template Spreadsheet hosted by Odoo by clicking on the provided link. You might get a warning that “Apps Script file [...] will also be copied”, which is expected - the script in question is used to fetch the data from your database.
3. You’ll need to provide your credentials (URL, database name, user credentials) to the script hosted within the template to access your database remotely. To do so, click on Odoo > Settings. You might be prompted to provide access to your Google Drive account to an application named Odoo Template - you’ll need to grant this authorization for the spreadsheet to work properly. 
4. Once your credentials are set up, paste the formula provided in the dialog in Odoo inside a cell of the spreadsheet - the data will be fetched automatically from your Odoo instance.
What exactly do I need to do?
If you are hosted on Odoo.com: nothing. Everything will be handled for you by October 3rd and the switch will happen invisibly on that day, without any configuration changes.
If you are hosted elsewhere (on your own server, partner server or on Odoo.sh), make sure to update the Odoo source code before October 3rd or ask your partner to ensure that your code is up-to-date for that date. If your code is up-to-date, the change will occur transparently on October 3, without any further action on your part (it is not necessary to update the modules themselves).
What about... ?
What about my existing Google Spreadsheets?
Existing Google Spreadsheets will keep working normally.
What about Odoo 12 (or earlier)?
These versions are no longer officially supported and will not be updated to work with these changes - both integrations will stop working on October 3rd, 2022.
What about Odoo 16 (or later)?
These integrations are removed from future versions of Odoo. Instead, we advise you to use the Odoo Documents integration (and to push your data in an Odoo Spreadsheet).
If you upgrade to Odoo 16 from an earlier version, it will not be possible to create new Google Drive documents but existing spreadsheets should keep working as they did before, assuming the data being fetched still exists in the same format in Odoo 16.