By Bhavya Mehta, Technical Account Manager
When a major healthcare customer began migrating its web security infrastructure from a long-trusted legacy vendor to Fortinet, I watched the transition hit turbulence almost immediately. Within weeks of go-live, confidence started to erode. Traffic inspection behaved inconsistently, authentication failed intermittently, and DLP checks that should have taken seconds were dragging on for minutes. For a team accustomed to the predictability of their previous platform, the new environment felt like a step backward — and the migration was put on hold.
As the Technical Account Manager on this account, I had a front-row seat to just how close we came to losing this customer's confidence entirely. What followed was a two-month escalation that tested our technical depth as much as our ability to hold a relationship together while the answers were still being worked out.
The Breaking Point
The first cracks appeared in ICAP-based content inspection. DLP test files were blocked instantly on the first attempt, but repeat submissions of the same file introduced delays of one to two minutes. Around the same time, Kerberos authentication was silently failing and falling back to NTLM — breaking single sign-on expectations and generating a steady stream of confused support tickets. Each issue on its own would have been manageable. Together, they created the impression of a platform that simply wasn't ready, and I felt that pressure in every customer call.
What Was Actually Broken
Our technical escalation engineering team went deep into packet captures and log correlation and eventually isolated three distinct, compounding root causes:
ICAP encoding mismatch combined with content-encoding and timeout behavior. The proxy and the remote ICAP servers weren't consistently aligned on how content encoding was being negotiated, which caused certain responses to be misinterpreted mid-stream. Combined with tight timeout thresholds, this produced the erratic pattern of instant first-pass blocks followed by long delays on repeat scans, as the proxy re-negotiated and retried encoding before timing out.
ICAP buffer exhaustion. Under sustained traffic, the ICAP buffer was filling up faster than it could be cleared, creating a backlog that queued legitimate requests behind it. This explained why latency worsened specifically on repeated or higher-volume test traffic rather than appearing consistently.
Incorrect keytab references for Kerberos authentication. Kerberos ticket validation was pointing to keytab details that didn't correctly match the service principal configuration, causing authentication to silently fail and fall back to NTLM instead of throwing a hard error — which is exactly why the issue was so difficult to isolate at first.
The Fix
Resolving the ICAP issue required correcting the content-encoding negotiation logic and adjusting timeout thresholds so the proxy and ICAP servers stayed in sync, paired with buffer-sizing changes to prevent the queue backlog under load. On the authentication side, the fix came down to correcting the keytab reference so Kerberos tickets validated against the right service principal — restoring reliable SSO behavior without any fallback to NTLM. Each change was validated individually and then together, using repeated DLP test cycles, to confirm the fixes held under real traffic conditions without reintroducing any of the original symptoms.
Holding the Line With the Customer
While the technical team worked the root cause, my job was to make sure the customer never felt like they were shouting into a void. That meant honest, frequent status updates even when the diagnosis wasn't finished, translating packet-level findings into terms their leadership could act on, and being upfront about timelines rather than overpromising. Trust doesn't come back just because a bug gets fixed — it comes back because people feel heard while it's being fixed. That was the part of this escalation I owned every day for two months.
From Escalation to Endorsement
Two months of iterative debugging, cross-functional coordination, and rigorous validation later, the picture had changed completely. ICAP latency dropped to expected levels, Kerberos authentication held reliably, and DLP inspection performed consistently under real-world load. The customer, who had been ready to walk back their migration, instead acknowledged the resolution and greenlit continuation of the rollout.
Why It Matters
Migrations between security vendors are inherently high-stakes: customers compare every rough edge against years of familiarity with their previous platform. This escalation reinforced something I try to carry into every account I manage — technical resolution and relationship management aren't separate tracks, they converge. Fixing the encoding, buffer, and keytab issues restored the technology. Staying present and transparent with the customer restored the trust. Both were necessary to get this migration back on track.