All of a Sudden Unable to Open PhotoShop

[robschamberger]

I'm being told that I don't have an active plan anymore, even though I do. I upgraded last month, but it's all under the same account. I have an older computer and can not upgrade to the OS needed for the latest version of PS in case I just needed to reinstall it.

How can I sign back in to PS CS6 without having to buy a whole new computer? This is maddening and the virtual assistant was utterly useless. Now I'm being asked for a serial number trying to get back in and I don't have a serial number and can't locate it.

[Abambo]

I'm being told that I don't have an active plan anymore, even though I do. I upgraded last month, but it's all under the same account.

By @robschamberger

What did you upgrade?

Do you have a subscription or a perpetual licence?

What is your OS and version?

[John T Smith]

For a subscription

Revert to trial https://helpx.adobe.com/manage-account-membership/cc-reverts-to-trial.html may help
-and troubleshooting FAQ https://community.adobe.com/t5/Get-Started/Troubleshooting-FAQ-What-should-I-do-if-I-have-a-membersh...
-and https://helpx.adobe.com/creative-cloud/kb/cloud-website-shows-trial-purchase.html

To download an older subscription version for your operating system

Direct Download Links https://prodesigntools.com/tag/ddl MAY help
-you MUST do what it says in Note: Very Important Instructions
-https://prodesigntools.com/adobe-cc-2015-direct-download-links.html#download-instructions
-the prodesign links go directly to Adobe's file server, so this process will
--only work until Adobe completely removes the old version(s) from the server
.
IF/When you do have a download, be sure to copy it to AT LEAST one external device
-since Adobe does sometimes remove old versions from the server
-a usb flash drive or external hard drive, or write to a DVD
-plus a text file containing your serial number if you have CS6/CS5

For CS6 read 

-Cloud takes over https://community.adobe.com/t5/Get-Started/Get-off-the-cloud/td-p/8075485 for some ideas

-As soon as you install any part of the Cloud, even a trial, it replaces your program management system
-if you plan to keep using a serial number program you should NOT install a Cloud program, not even a trial

Lost information https://community.adobe.com/t5/Premiere-Pro/Find-serial-number-without-Adpbe-ID/td-p/7769446
- page has links to programs to find an installed serial number in Mac or Windows
- Also https://helpx.adobe.com/download-install/kb/find-serial-number.html
- when you find your serial number(s) write them down and put in a desk drawer

[Nancy OShea]

Did you purchase CS6 when it was still available?

CS5 and CS6 are on life support. But they can still be activated providing you have the following:
1. your original media (disks or downloads) you received at purchase and a way to read them,
2. a legitimate serial number for that version, language and platform (Win/Mac) and if it was an upgrade, a qualifying serial number from an older product,
3. an older operating system that can support legacy 32-bit apps.

Before you install CS6, run the Adobe Cleaner tools to remove apps from your system.

https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html

NOTE 1 : Creative Suite installers won't work on macOS Sierra, High Sierra or Mojave without terminal workarounds. See the help article below.
https://helpx.adobe.com/creative-cloud/kb/install-creative-suite-mac-os-sierra.html

NOTE 2: Legacy Creative Suite will never run on Catalina or Big Sur. Only the latest Creative Cloud products are compatible.

NOTE 3: Legacy Creative Suite is discontinued & unsupported. Use at your own risk.