MT4 cannot attach an EA to chart err cannot open file 'C:\Users\admin\AppData\Roaming\MetaQuotes\Terminal

External question — Stack Overflow Stack Exchange Author: increase Original post: https://stackoverflow.com/questions/73540676 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I am running MT4 Terminal build 1349 and cannot attach an EA to the chart, I receive this error in the experts tab 2022.08.30 12:06:41.009 cannot open file 'C:\Users\admin\AppData\Roaming\MetaQuotes\Terminal\03B7A903FC18E495C3D573C316883A0E\MQL4\Experts\Moving Average.ex4' [2]

External answer — Stack Overflow Stack Exchange Author: Filip Valkovič Original post: https://stackoverflow.com/a/76039258 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. few things to check: 1.name of the file suggest that it is rather an indicator and not EA ? so correct folder for the file is MQL4\Indicators\Moving Average.ex4' and then also it will be added on chart from list of indicators and not experts. 2.there also can be another file with same name in indicators, so try renaming your EA 3.when adding programs to chart, sometimes Metatrader tries to recompile them, so .ex4 file is irrelevant, and you need to have source code file .mq4 (THIS IS VERY IMPORTANT FOR INDICATORS ! ) 4.Metatrader simply cannot access the folder/file, because its forbidden from OS itself (Windows) or file is opened in some external editor, so check if file is not being used in any other way, and that access rights settings of the file allow read/write