How to update a twenty-year-old company systems without stopping work

The average project is fine

Most system updates run a little over. A few blow up, and those are the ones that close a business.

Oxford researchers Flyvbjerg and Budzier studied 1,471 IT projects and found the average cost overrun was 27 percent. The same Oxford study found that 1 in 6 projects was what they call a Black Swan, with a cost overrun of 200 percent on average and a schedule overrun of almost 70 percent. You are not trying to hit the average. You are trying to stay out of the 1 in 6.

Never switch everything at once

A big bang cutover is when you turn off the old system and turn on the new one on the same day. It is the fastest way into the 1 in 6.

The clearest picture of this is a bank, not a contractor, but the lesson holds. In April 2018 TSB moved its whole core banking platform in one cutover, and the UK Financial Conduct Authority says the move disrupted all branches and a significant proportion of its 5.2 million customers. The FCA says it took until December of that year, about 8 months, for the bank to return to business as usual. UK regulators fined TSB 48.65 million pounds, and the FCA press release says TSB paid another 32.7 million pounds in redress to harmed customers. Your company is smaller. Your version of this is a month of missed invoices and a phone that rings to nowhere.

Old systems get replaced quietly

Failures make the news. Successes do not.

Federal agencies told GAO they had successfully modernized at least 94 legacy systems in 5 years, mostly by rewriting old code or moving services to the cloud. GAO names none of them, which is the point. GAO also reports that roughly 80 percent of the federal government's more than 100 billion dollars a year in IT spend goes to running and maintaining what already exists. You pay a version of that too, every time a tech retypes a paper work order into a spreadsheet.

Write the plan on one page

A plan with no dates is a wish. GAO says a real plan needs three things.

Of the 11 most critical federal systems GAO reviewed, only 9 had any documented modernization plan, and 6 of those 9 plans were incomplete. Two had no plan at all. GAO says a minimum plan needs milestones, a description of the work, and what happens to the old system when you are done. The same GAO review found 8 of the 11 systems ran outdated programming languages, 4 ran unsupported hardware or software, and 7 had known security holes. Write down which of those apply to yours, because the ones with security holes go first.

Some pieces cut over on a date

Accounting is the piece you usually cannot phase. The vendor sets the windows and you work inside them.

Intuit's own help pages set hard limits on moving from QuickBooks Desktop to QuickBooks Online. Intuit says the Desktop file must have fewer than 4,000,000 total list entries, which it calls targets, to import directly. Intuit says files near or above 2,000,000 targets carry more risk of inventory errors, and inventory history begins on the day you migrate. Intuit says the new Online account must be less than 90 days old, or 180 days if an accountant created it, to accept the move. For payroll, Intuit tells users to wait 2 to 3 business days after the last payroll run, then finish the move before the next one. In a QuickBooks Community thread, Intuit staff called a 13,000 target file small, and the user quoted Intuit guidance that an export can take up to 72 hours.

One more Intuit fact makes the cutover safer. Intuit says the old Desktop file stays open in view only mode for 1 year on QuickBooks Desktop 2023 R3 or newer. That is your safety net. You do not need the old books to work. You need to be able to read them.

Some pieces run side by side

Your customer list and your website can run on two systems at once. Accounting cannot, but these can.

HubSpot's import documentation shows why a customer list is the easy one. HubSpot says a free account can import files up to 20 MB and 500,000 rows in a rolling 24 hour period. HubSpot says a paid account can import files up to 512 MB, 1,048,576 rows per file, and 10,000,000 rows per day. Your whole list fits in one free import. Load it, keep the old list running, and compare the two for a few weeks before you turn anything off.

The website works the same way. Build the new one at a new address, keep the old one live, and switch when someone who is not you has tested it.

The numbers side by side

Every number here has a name next to it. Nothing came from memory.

What stays human

Software moves records. People decide which records are true.

During a side by side run, the old system and the new one will disagree on a customer's balance or a job's status. A person picks which one is right, every time. The payroll timing call is a person's call too, because Intuit gives you the 2 to 3 day window but does not know when your crew gets paid. And for 1 year after the accounting switch, someone has to be able to open the old file and read it when a customer calls about an old invoice. That reading is a human job.

What we got wrong

I started this piece thinking migrations usually fail. The data says otherwise.

The Oxford study puts the average overrun at 27 percent, which is survivable. The danger is the 1 in 6 tail, not the average. GAO's count of 94 quiet successes in 5 years says old systems get replaced all the time without anyone noticing. And TSB is a bank with 5.2 million customers and an outside supplier, not a 20 year old contractor, so it is a picture of what a big bang looks like, not a statistic about your business. I also thought everything could be phased. The Intuit windows show accounting has to cut over on a date, and knowing which pieces are which is most of the plan.

Have us look first

If you want the one page plan written for your shop, book the VuseDesk audit. We will sort your systems into the ones that cut over on a date and the ones that can run side by side, and tell you which goes first. You keep working the whole time.