MT4 Cannot Open File .ex4 Solution

I was testing out a new MT4 expert advisor (EA) .ex4 and found that it can’t be attached to a chart. The MT4 journal log simply prints

‘Cannot open file ‘C:\pathToMT4\experts\eaName.ex4’ on the chartName, timeFrame

The problem was easily solved by doing the following:

1. Open the .ex4 file in MetaEditor

2. Press F5 to compile it

3. Restart MT4 and voila, the EA now works on any chart.