Thank you for finally acknowledging that there were serious issues with your approach to licensing our content. Explicitly marking the license of each post is messy, but the best approach.

However, two major concerns and one minor remain:

1. If SE agrees that it didn't have the right to change the license of posts contributed under 3.0 to 4.0, then surely the same legal arguments apply to the 2.5 to 3.0 change. This apparently happened on 8 April 2011. Whatever technical solution ends up being implemented should also be capable of showing those really old posts as CC BY-SA 2.5.

2. Please fix the page footers to remove the "attribution required" link, as it violates the CC trademarks and was apparently deliberately removed from the TOS.

3. Currently the version number is not explicitly mentioned in the TOS, it is only revealed in the link to the license. Please explicitly add the version number to the text of the TOS each time you mention the CC BY-SA license. You should also consider changing it to say "4.0 or later", although note that that would add another epoch to the licensing history, as posts from between 2 May 2018 and whenever the TOS was updated could only be 4.0. Please also change the text of the TOS to say "CC BY-SA" rather than "CC-BY-SA".

Thank you for finally acknowledging that there were serious issues with your approach to licensing our content. Explicitly marking the license of each post is messy, but the best approach.

However, two major concerns and one minor remain:

1. If SE agrees that it didn't have the right to change the license of posts contributed under 3.0 to 4.0, then surely the same legal arguments apply to the 2.5 to 3.0 change. This apparently happened on 8 April 2011. Whatever technical solution ends up being implemented should also be capable of showing those really old posts as CC BY-SA 2.5.

2. Please fix the page footers to remove the "attribution required" link, as it violates the CC trademarks and was apparently deliberately removed from the TOS.

3. Currently the version number is not explicitly mentioned in the TOS, it is only revealed in the link to the license. Please explicitly add the version number to the text of the TOS each time you mention the CC BY-SA license. You should also consider changing it to say "4.0 or later", although note that that would add another epoch to the licensing history, as posts from between 2 May 2018 and whenever the TOS was updated could only be 4.0. Please also change the text of the TOS to say "CC BY-SA" rather than "CC-BY-SA".

Has there been an internal review into how all these mistakes happened? Have you changed lawyers since then? Because any lawyer worth their salt should know what an integration clause is and should never have approved the old TOS including SE's bespoke "attribution required" rules. Competent lawyers would have told you that you can't upgrade people's posts from the CC BY-SA 3.0 to 4.0 license without their express permission. These are not complicated legal questions.