Missing a square in latch hook can mean two different things: leaving one physical canvas position empty, or skipping a chart cell while reading and then placing later colors one position out of alignment. The repair depends on which mistake happened.
Before fixing anything, determine whether there is a real empty mesh position or a counting shift in the row. One isolated gap is usually simple to fill; a shifted pattern requires returning to the last point where chart and canvas still matched.
Check whether a knot is missing or the whole sequence shifted
Separate the pile with your fingers and inspect the canvas from both front and reverse.
If one bar or position is clearly empty while neighboring colors still match the chart, a single knot was probably missed.
If there is no physical gap but color boundaries appear one position too early or late, you may have skipped a chart cell while reading.
Count from a known reference such as an edge, a ten-position mark or a major color change.
Compare the number of knots in the row with the number of cells that should have been completed.
Do not begin the repair until the problem is identified; filling an empty position does not correct a shifted color sequence.
If one position is empty, fill it as soon as you notice
When the empty position is still near the active work area, move neighboring pile aside and locate the correct canvas bar.
Check the chart to confirm exactly which color belongs in that cell.
Use a strand cut to the same length as the surrounding yarn and make a normal knot on the empty bar.
Center the yarn and seat it with the same tension as neighboring knots so the replacement does not stand high or low.
Then recount the row and confirm that the total now matches.
A correctly filled isolated gap does not require removing the surrounding knots.
If the gap is buried under pile, approach it from the reverse
In a more advanced area, finished pile can completely hide the mesh from the front.
Turn the piece over and locate the unknotted bar from behind. Repeating knot structures often make an empty position easier to see on the reverse.
Separate neighboring yarn with your fingers and guide the tool through the canvas openings without catching completed knots.
If the space is tight, work slowly and do not pull correct knots loose simply to make room.
After adding the missing strand, return to the front and redistribute the pile with your fingers.
Check that the repair covers the gap without lifting or loosening the surrounding tufts.
If a chart cell was skipped, return to the last correct checkpoint
When later colors are shifted, adding one extra knot at the end of the row does not repair the image.
Locate the last position where chart and canvas definitely agree.
From there, identify how many later knots were placed using the shifted sequence.
Remove and remake only the affected section when the mistake is recent. Correcting ten knots is better than carrying the offset through another hundred.
Do not simply move every future color one cell as an improvised compensation because that creates a second pattern logic that is hard to track.
Mark the corrected row clearly on the working copy before continuing.
Use intermediate references to catch skipped positions earlier
On long rows, divide the width into groups of ten or twenty positions and verify each group.
When safe, place matching reference marks on the canvas margin and the chart.
Major color changes, diagonals and shape edges make useful visual checkpoints.
At the end of a row, do more than count the total; confirm that one or two important color boundaries sit in the correct columns.
A ruler or strip placed beneath the active chart row greatly reduces the chance of jumping to the next line.
Small checks during the work are much faster than repairing a large shifted section later.
Do not confuse a missed square with a coverage gap
Sometimes canvas appears between tufts even though every position actually contains a knot.
Separate the pile and inspect the reverse before adding an extra strand.
Yarn that is too thin, badly centered pieces or inconsistent knot direction can create a visual opening in the surface.
Adding another knot where one already exists crowds the canvas and can distort the mesh.
When all positions are occupied, improve coverage by grooming, repositioning or replacing the problematic knot instead of doubling it.
If you miss a square in latch hook, the key is distinguishing a genuinely empty position from a shifted chart reading. Fill an isolated gap, but repair a shifted sequence by returning to the last checkpoint where chart and canvas still matched.