Based on what you describe, there are two different things happening:

1. The normal validation errors for SSL certificates (wrong format, wrong password, missing chain, etc.).
2. A generic “Something went wrong processing your request” / “There was an error processing your request” coming from LifeTime when:
   • Uploading a new PFX on one specific environment.
   • Deleting old/expired certificates.

The first category is covered by the usual validation messages you’d see (public/private key extraction issues, wrong password, chain error, etc.). Possible errors when validating your SSL domain certificate
In your case, however, you’re getting a generic platform error instead of one of those specific messages. That usually points to a LifeTime/infra problem rather than an issue with the certificate itself.

Given that:

• The same process and PFX format worked for other environments.
• You can’t even delete old certificates (which doesn’t depend on certificate content at all).
• You already opened a support ticket.

This strongly suggests some kind of LifeTime / infrastructure issue (for example, corrupted records for that environment’s certificates, internal exception in the certificate management module, or a limit/constraint reached internally) that only OutSystems Support can fix from their side. It isn’t something you can resolve purely with configuration in Service Center/LifeTime.

What you can still double‑check on your side (to rule out the “usual suspects”):

1. Confirm the PFX itself is valid:

   • PFX contains private key + public key + full chain and uses a supported key size (≤ 4096 bits). Use your SSL domain in OutSystems Cloud
   • Password is correct and you can open it locally (e.g. with OpenSSL or the OS certificate manager).

2. Try the same PFX on:

   • Another environment (just for validation; you don’t need to assign it), to confirm the file itself is OK.
   • Or, if you already used that exact PFX on another environment successfully, mention that explicitly in the support ticket.

3. Check certificate chain completeness:

   • Make sure the certificate you’re uploading includes the full chain (root + intermediate + domain), or that the chain field is correctly filled if you’re using PEM. Missing/incorrect chains usually give a “Chain error” / “Unable to verify first certificate” on the consumer side. Use your SSL domain in OutSystems Cloud

If all that is OK and you still get the generic “Something went wrong processing your request” both when uploading and deleting:

• Capture the exact timestamp and environment name.
• Provide those details (and that it’s reproducible only on this environment, plus the fact that deletion also fails) to Support.

From community experience with similar symptoms, the resolution typically ends up being:

• OutSystems Support fixing something in their backend (e.g. cleaning or correcting a problematic record in the Domain Certificates area, or fixing a bug affecting that LifeTime version/tenant).
• After they do that, the same upload/delete operations start working again, without any change in your certificate files.

So in short: if the PFX and chain are already validated and the error remains generic and environment‑specific, this is most likely a platform-side issue, and the support ticket is the right and necessary path; there isn’t a known “self‑service” workaround from the UI in that scenario.